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<h2><span class="refentrytitle"><a name="gobject-Type-Information.top_of_page"></a>Type Information</span></h2>
<p>Type Information — The GLib Runtime type identification and
management system</p>
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<div class="refsynopsisdiv" title="Synopsis">
<a name="gobject-Type-Information.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">
#include &lt;glib-object.h&gt;
typedef <a class="link" href="gobject-Type-Information.html#GType" title="GType">GType</a>;
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FUNDAMENTAL:CAPS" title="G_TYPE_FUNDAMENTAL()">G_TYPE_FUNDAMENTAL</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FUNDAMENTAL-MAX:CAPS" title="G_TYPE_FUNDAMENTAL_MAX">G_TYPE_FUNDAMENTAL_MAX</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-MAKE-FUNDAMENTAL:CAPS" title="G_TYPE_MAKE_FUNDAMENTAL()">G_TYPE_MAKE_FUNDAMENTAL</a> (x)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-ABSTRACT:CAPS" title="G_TYPE_IS_ABSTRACT()">G_TYPE_IS_ABSTRACT</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-DERIVED:CAPS" title="G_TYPE_IS_DERIVED()">G_TYPE_IS_DERIVED</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-FUNDAMENTAL:CAPS" title="G_TYPE_IS_FUNDAMENTAL()">G_TYPE_IS_FUNDAMENTAL</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-VALUE-TYPE:CAPS" title="G_TYPE_IS_VALUE_TYPE()">G_TYPE_IS_VALUE_TYPE</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-HAS-VALUE-TABLE:CAPS" title="G_TYPE_HAS_VALUE_TABLE()">G_TYPE_HAS_VALUE_TABLE</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-CLASSED:CAPS" title="G_TYPE_IS_CLASSED()">G_TYPE_IS_CLASSED</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-INSTANTIATABLE:CAPS" title="G_TYPE_IS_INSTANTIATABLE()">G_TYPE_IS_INSTANTIATABLE</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-DERIVABLE:CAPS" title="G_TYPE_IS_DERIVABLE()">G_TYPE_IS_DERIVABLE</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-DEEP-DERIVABLE:CAPS" title="G_TYPE_IS_DEEP_DERIVABLE()">G_TYPE_IS_DEEP_DERIVABLE</a> (type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-IS-INTERFACE:CAPS" title="G_TYPE_IS_INTERFACE()">G_TYPE_IS_INTERFACE</a> (type)
<a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface">GTypeInterface</a>;
<a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance">GTypeInstance</a>;
<a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass">GTypeClass</a>;
<a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo">GTypeInfo</a>;
<a class="link" href="gobject-Type-Information.html#GTypeFundamentalInfo" title="GTypeFundamentalInfo">GTypeFundamentalInfo</a>;
<a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo">GInterfaceInfo</a>;
<a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable">GTypeValueTable</a>;
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FROM-INSTANCE:CAPS" title="G_TYPE_FROM_INSTANCE()">G_TYPE_FROM_INSTANCE</a> (instance)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FROM-CLASS:CAPS" title="G_TYPE_FROM_CLASS()">G_TYPE_FROM_CLASS</a> (g_class)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FROM-INTERFACE:CAPS" title="G_TYPE_FROM_INTERFACE()">G_TYPE_FROM_INTERFACE</a> (g_iface)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INSTANCE-GET-CLASS:CAPS" title="G_TYPE_INSTANCE_GET_CLASS()">G_TYPE_INSTANCE_GET_CLASS</a> (instance,
g_type,
c_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INSTANCE-GET-INTERFACE:CAPS" title="G_TYPE_INSTANCE_GET_INTERFACE()">G_TYPE_INSTANCE_GET_INTERFACE</a> (instance,
g_type,
c_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INSTANCE-GET-PRIVATE:CAPS" title="G_TYPE_INSTANCE_GET_PRIVATE()">G_TYPE_INSTANCE_GET_PRIVATE</a> (instance,
g_type,
c_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-INSTANCE:CAPS" title="G_TYPE_CHECK_INSTANCE()">G_TYPE_CHECK_INSTANCE</a> (instance)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-INSTANCE-CAST:CAPS" title="G_TYPE_CHECK_INSTANCE_CAST()">G_TYPE_CHECK_INSTANCE_CAST</a> (instance,
g_type,
c_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-INSTANCE-TYPE:CAPS" title="G_TYPE_CHECK_INSTANCE_TYPE()">G_TYPE_CHECK_INSTANCE_TYPE</a> (instance,
g_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-CLASS-CAST:CAPS" title="G_TYPE_CHECK_CLASS_CAST()">G_TYPE_CHECK_CLASS_CAST</a> (g_class,
g_type,
c_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-CLASS-TYPE:CAPS" title="G_TYPE_CHECK_CLASS_TYPE()">G_TYPE_CHECK_CLASS_TYPE</a> (g_class,
g_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-VALUE:CAPS" title="G_TYPE_CHECK_VALUE()">G_TYPE_CHECK_VALUE</a> (value)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHECK-VALUE-TYPE:CAPS" title="G_TYPE_CHECK_VALUE_TYPE()">G_TYPE_CHECK_VALUE_TYPE</a> (value,
g_type)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FLAG-RESERVED-ID-BIT:CAPS" title="G_TYPE_FLAG_RESERVED_ID_BIT">G_TYPE_FLAG_RESERVED_ID_BIT</a>
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-init" title="g_type_init ()">g_type_init</a> (<em class="parameter"><code><span class="type">void</span></code></em>);
enum <a class="link" href="gobject-Type-Information.html#GTypeDebugFlags" title="enum GTypeDebugFlags">GTypeDebugFlags</a>;
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-init-with-debug-flags" title="g_type_init_with_debug_flags ()">g_type_init_with_debug_flags</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeDebugFlags" title="enum GTypeDebugFlags"><span class="type">GTypeDebugFlags</span></a> debug_flags</code></em>);
const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="returnvalue">gchar</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-name" title="g_type_name ()">g_type_name</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="returnvalue">GQuark</span></a> <a class="link" href="gobject-Type-Information.html#g-type-qname" title="g_type_qname ()">g_type_qname</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-from-name" title="g_type_from_name ()">g_type_from_name</a> (<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *name</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-parent" title="g_type_parent ()">g_type_parent</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="returnvalue">guint</span></a> <a class="link" href="gobject-Type-Information.html#g-type-depth" title="g_type_depth ()">g_type_depth</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-next-base" title="g_type_next_base ()">g_type_next_base</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> leaf_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> root_type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> <a class="link" href="gobject-Type-Information.html#g-type-is-a" title="g_type_is_a ()">g_type_is_a</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> is_a_type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-class-ref" title="g_type_class_ref ()">g_type_class_ref</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-class-peek" title="g_type_class_peek ()">g_type_class_peek</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-class-peek-static" title="g_type_class_peek_static ()">g_type_class_peek_static</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-class-unref" title="g_type_class_unref ()">g_type_class_unref</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-class-peek-parent" title="g_type_class_peek_parent ()">g_type_class_peek_parent</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-class-add-private" title="g_type_class_add_private ()">g_type_class_add_private</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gsize"><span class="type">gsize</span></a> private_size</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-add-class-private" title="g_type_add_class_private ()">g_type_add_class_private</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> class_type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gsize"><span class="type">gsize</span></a> private_size</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-interface-peek" title="g_type_interface_peek ()">g_type_interface_peek</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> instance_class</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> iface_type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-interface-peek-parent" title="g_type_interface_peek_parent ()">g_type_interface_peek_parent</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-default-interface-ref" title="g_type_default_interface_ref ()">g_type_default_interface_ref</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> g_type</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-default-interface-peek" title="g_type_default_interface_peek ()">g_type_default_interface_peek</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> g_type</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-default-interface-unref" title="g_type_default_interface_unref ()">g_type_default_interface_unref</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-children" title="g_type_children ()">g_type_children</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> *n_children</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-interfaces" title="g_type_interfaces ()">g_type_interfaces</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> *n_interfaces</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-interface-prerequisites" title="g_type_interface_prerequisites ()">g_type_interface_prerequisites</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> *n_prerequisites</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-set-qdata" title="g_type_set_qdata ()">g_type_set_qdata</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> quark</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> data</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> <a class="link" href="gobject-Type-Information.html#g-type-get-qdata" title="g_type_get_qdata ()">g_type_get_qdata</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> quark</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-query" title="g_type_query ()">g_type_query</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeQuery" title="GTypeQuery"><span class="type">GTypeQuery</span></a> *query</code></em>);
<a class="link" href="gobject-Type-Information.html#GTypeQuery" title="GTypeQuery">GTypeQuery</a>;
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()">*GBaseInitFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GBaseFinalizeFunc" title="GBaseFinalizeFunc ()">*GBaseFinalizeFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()">*GClassInitFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> class_data</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GClassFinalizeFunc" title="GClassFinalizeFunc ()">*GClassFinalizeFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> class_data</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GInstanceInitFunc" title="GInstanceInitFunc ()">*GInstanceInitFunc</a>) (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> *instance</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GInterfaceInitFunc" title="GInterfaceInitFunc ()">*GInterfaceInitFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> iface_data</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GInterfaceFinalizeFunc" title="GInterfaceFinalizeFunc ()">*GInterfaceFinalizeFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> iface_data</code></em>);
<a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> (<a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()">*GTypeClassCacheFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> cache_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> *g_class</code></em>);
enum <a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags">GTypeFlags</a>;
enum <a class="link" href="gobject-Type-Information.html#GTypeFundamentalFlags" title="enum GTypeFundamentalFlags">GTypeFundamentalFlags</a>;
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-register-static" title="g_type_register_static ()">g_type_register_static</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> parent_type</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> *info</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-register-static-simple" title="g_type_register_static_simple ()">g_type_register_static_simple</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> parent_type</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> class_size</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><span class="type">GClassInitFunc</span></a> class_init</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> instance_size</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GInstanceInitFunc" title="GInstanceInitFunc ()"><span class="type">GInstanceInitFunc</span></a> instance_init</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-register-dynamic" title="g_type_register_dynamic ()">g_type_register_dynamic</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> parent_type</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code><a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> *plugin</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-register-fundamental" title="g_type_register_fundamental ()">g_type_register_fundamental</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type_id</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> *info</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GTypeFundamentalInfo" title="GTypeFundamentalInfo"><span class="type">GTypeFundamentalInfo</span></a> *finfo</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-add-interface-static" title="g_type_add_interface_static ()">g_type_add_interface_static</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> instance_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> *info</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-add-interface-dynamic" title="g_type_add_interface_dynamic ()">g_type_add_interface_dynamic</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> instance_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code><a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> *plugin</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-interface-add-prerequisite" title="g_type_interface_add_prerequisite ()">g_type_interface_add_prerequisite</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> prerequisite_type</code></em>);
<a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="returnvalue">GTypePlugin</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-get-plugin" title="g_type_get_plugin ()">g_type_get_plugin</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="returnvalue">GTypePlugin</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-interface-get-plugin" title="g_type_interface_get_plugin ()">g_type_interface_get_plugin</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> instance_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-fundamental-next" title="g_type_fundamental_next ()">g_type_fundamental_next</a> (<em class="parameter"><code><span class="type">void</span></code></em>);
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> <a class="link" href="gobject-Type-Information.html#g-type-fundamental" title="g_type_fundamental ()">g_type_fundamental</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type_id</code></em>);
<a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="returnvalue">GTypeInstance</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-create-instance" title="g_type_create_instance ()">g_type_create_instance</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-free-instance" title="g_type_free_instance ()">g_type_free_instance</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> *instance</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-add-class-cache-func" title="g_type_add_class_cache_func ()">g_type_add_class_cache_func</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> cache_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> cache_func</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-remove-class-cache-func" title="g_type_remove_class_cache_func ()">g_type_remove_class_cache_func</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> cache_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> cache_func</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-class-unref-uncached" title="g_type_class_unref_uncached ()">g_type_class_unref_uncached</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-add-interface-check" title="g_type_add_interface_check ()">g_type_add_interface_check</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> check_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInterfaceCheckFunc" title="GTypeInterfaceCheckFunc ()"><span class="type">GTypeInterfaceCheckFunc</span></a> check_func</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gobject-Type-Information.html#g-type-remove-interface-check" title="g_type_remove_interface_check ()">g_type_remove_interface_check</a> (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> check_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInterfaceCheckFunc" title="GTypeInterfaceCheckFunc ()"><span class="type">GTypeInterfaceCheckFunc</span></a> check_func</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gobject-Type-Information.html#GTypeInterfaceCheckFunc" title="GTypeInterfaceCheckFunc ()">*GTypeInterfaceCheckFunc</a>) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> check_data</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>);
<a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="returnvalue">GTypeValueTable</span></a>* <a class="link" href="gobject-Type-Information.html#g-type-value-table-peek" title="g_type_value_table_peek ()">g_type_value_table_peek</a> (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE:CAPS" title="G_DEFINE_TYPE()">G_DEFINE_TYPE</a> (TN,
t_n,
T_P)
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-WITH-CODE:CAPS" title="G_DEFINE_TYPE_WITH_CODE()">G_DEFINE_TYPE_WITH_CODE</a> (TN,
t_n,
T_P,
_C_)
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-ABSTRACT-TYPE:CAPS" title="G_DEFINE_ABSTRACT_TYPE()">G_DEFINE_ABSTRACT_TYPE</a> (TN,
t_n,
T_P)
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-ABSTRACT-TYPE-WITH-CODE:CAPS" title="G_DEFINE_ABSTRACT_TYPE_WITH_CODE()">G_DEFINE_ABSTRACT_TYPE_WITH_CODE</a> (TN,
t_n,
T_P,
_C_)
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-INTERFACE:CAPS" title="G_DEFINE_INTERFACE()">G_DEFINE_INTERFACE</a> (TN,
t_n,
T_P)
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-INTERFACE-WITH-CODE:CAPS" title="G_DEFINE_INTERFACE_WITH_CODE()">G_DEFINE_INTERFACE_WITH_CODE</a> (TN,
t_n,
T_P,
_C_)
#define <a class="link" href="gobject-Type-Information.html#G-IMPLEMENT-INTERFACE:CAPS" title="G_IMPLEMENT_INTERFACE()">G_IMPLEMENT_INTERFACE</a> (TYPE_IFACE,
iface_init)
#define <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()">G_DEFINE_TYPE_EXTENDED</a> (TN,
t_n,
T_P,
_f_,
_C_)
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INVALID:CAPS" title="G_TYPE_INVALID">G_TYPE_INVALID</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-NONE:CAPS" title="G_TYPE_NONE">G_TYPE_NONE</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INTERFACE:CAPS" title="G_TYPE_INTERFACE">G_TYPE_INTERFACE</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-CHAR:CAPS" title="G_TYPE_CHAR">G_TYPE_CHAR</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-UCHAR:CAPS" title="G_TYPE_UCHAR">G_TYPE_UCHAR</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-BOOLEAN:CAPS" title="G_TYPE_BOOLEAN">G_TYPE_BOOLEAN</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INT:CAPS" title="G_TYPE_INT">G_TYPE_INT</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-UINT:CAPS" title="G_TYPE_UINT">G_TYPE_UINT</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-LONG:CAPS" title="G_TYPE_LONG">G_TYPE_LONG</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-ULONG:CAPS" title="G_TYPE_ULONG">G_TYPE_ULONG</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-INT64:CAPS" title="G_TYPE_INT64">G_TYPE_INT64</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-UINT64:CAPS" title="G_TYPE_UINT64">G_TYPE_UINT64</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-ENUM:CAPS" title="G_TYPE_ENUM">G_TYPE_ENUM</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FLAGS:CAPS" title="G_TYPE_FLAGS">G_TYPE_FLAGS</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-FLOAT:CAPS" title="G_TYPE_FLOAT">G_TYPE_FLOAT</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-DOUBLE:CAPS" title="G_TYPE_DOUBLE">G_TYPE_DOUBLE</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-STRING:CAPS" title="G_TYPE_STRING">G_TYPE_STRING</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-POINTER:CAPS" title="G_TYPE_POINTER">G_TYPE_POINTER</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-BOXED:CAPS" title="G_TYPE_BOXED">G_TYPE_BOXED</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-PARAM:CAPS" title="G_TYPE_PARAM">G_TYPE_PARAM</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-OBJECT:CAPS" title="G_TYPE_OBJECT">G_TYPE_OBJECT</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-GTYPE:CAPS" title="G_TYPE_GTYPE">G_TYPE_GTYPE</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-RESERVED-GLIB-FIRST:CAPS" title="G_TYPE_RESERVED_GLIB_FIRST">G_TYPE_RESERVED_GLIB_FIRST</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-RESERVED-GLIB-LAST:CAPS" title="G_TYPE_RESERVED_GLIB_LAST">G_TYPE_RESERVED_GLIB_LAST</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-RESERVED-BSE-FIRST:CAPS" title="G_TYPE_RESERVED_BSE_FIRST">G_TYPE_RESERVED_BSE_FIRST</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-RESERVED-BSE-LAST:CAPS" title="G_TYPE_RESERVED_BSE_LAST">G_TYPE_RESERVED_BSE_LAST</a>
#define <a class="link" href="gobject-Type-Information.html#G-TYPE-RESERVED-USER-FIRST:CAPS" title="G_TYPE_RESERVED_USER_FIRST">G_TYPE_RESERVED_USER_FIRST</a>
</pre>
</div>
<div class="refsect1" title="Description">
<a name="gobject-Type-Information.description"></a><h2>Description</h2>
<p>
The GType API is the foundation of the GObject system. It provides the
facilities for registering and managing all fundamental data types,
user-defined object and interface types. Before using any GType
or GObject functions, <a class="link" href="gobject-Type-Information.html#g-type-init" title="g_type_init ()"><code class="function">g_type_init()</code></a> must be called to initialize the
type system.
</p>
<p>
For type creation and registration purposes, all types fall into one of
two categories: static or dynamic. Static types are never loaded or
unloaded at run-time as dynamic types may be. Static types are created
with <a class="link" href="gobject-Type-Information.html#g-type-register-static" title="g_type_register_static ()"><code class="function">g_type_register_static()</code></a> that gets type specific information passed
in via a <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure.
Dynamic types are created with <a class="link" href="gobject-Type-Information.html#g-type-register-dynamic" title="g_type_register_dynamic ()"><code class="function">g_type_register_dynamic()</code></a> which takes a
<a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure instead. The remaining type information (the
<a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure) is retrieved during runtime through <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a>
and the g_type_plugin_*() API.
These registration functions are usually called only once from a
function whose only purpose is to return the type identifier for a
specific class. Once the type (or class or interface) is registered,
it may be instantiated, inherited, or implemented depending on exactly
what sort of type it is.
There is also a third registration function for registering fundamental
types called <a class="link" href="gobject-Type-Information.html#g-type-register-fundamental" title="g_type_register_fundamental ()"><code class="function">g_type_register_fundamental()</code></a> which requires both a <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>
structure and a <a class="link" href="gobject-Type-Information.html#GTypeFundamentalInfo" title="GTypeFundamentalInfo"><span class="type">GTypeFundamentalInfo</span></a> structure but it is seldom used
since most fundamental types are predefined rather than user-defined.
</p>
<p>
A final word about type names.
Such an identifier needs to be at least three characters long. There is no
upper length limit. The first character needs to be a letter (a-z or A-Z)
or an underscore '_'. Subsequent characters can be letters, numbers or
any of '-_+'.
</p>
</div>
<div class="refsect1" title="Details">
<a name="gobject-Type-Information.details"></a><h2>Details</h2>
<div class="refsect2" title="GType">
<a name="GType"></a><h3>GType</h3>
<p>
A numerical value which represents the unique identifier of a registered
type.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FUNDAMENTAL()">
<a name="G-TYPE-FUNDAMENTAL:CAPS"></a><h3>G_TYPE_FUNDAMENTAL()</h3>
<pre class="programlisting">#define G_TYPE_FUNDAMENTAL(type) (g_type_fundamental (type))
</pre>
<p>
The fundamental type which is the ancestor of <em class="parameter"><code>type</code></em>.
Fundamental types are types that serve as ultimate bases for the derived types,
thus they are the roots of distinct inheritance hierarchies.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FUNDAMENTAL_MAX">
<a name="G-TYPE-FUNDAMENTAL-MAX:CAPS"></a><h3>G_TYPE_FUNDAMENTAL_MAX</h3>
<pre class="programlisting">#define G_TYPE_FUNDAMENTAL_MAX (255 &lt;&lt; G_TYPE_FUNDAMENTAL_SHIFT)
</pre>
<p>
An integer constant that represents the number of identifiers reserved
for types that are assigned at compile-time.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_MAKE_FUNDAMENTAL()">
<a name="G-TYPE-MAKE-FUNDAMENTAL:CAPS"></a><h3>G_TYPE_MAKE_FUNDAMENTAL()</h3>
<pre class="programlisting">#define G_TYPE_MAKE_FUNDAMENTAL(x) ((GType) ((x) &lt;&lt; G_TYPE_FUNDAMENTAL_SHIFT))
</pre>
<p>
Get the type ID for the fundamental type number <em class="parameter"><code>x</code></em>.
Use <a class="link" href="gobject-Type-Information.html#g-type-fundamental-next" title="g_type_fundamental_next ()"><code class="function">g_type_fundamental_next()</code></a> instead of this macro to create new fundamental
types.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>the fundamental type number.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the GType
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_ABSTRACT()">
<a name="G-TYPE-IS-ABSTRACT:CAPS"></a><h3>G_TYPE_IS_ABSTRACT()</h3>
<pre class="programlisting">#define G_TYPE_IS_ABSTRACT(type) (g_type_test_flags ((type), G_TYPE_FLAG_ABSTRACT))
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is an abstract type. An abstract type can not be
instantiated and is normally used as an abstract base class for
derived classes.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_DERIVED()">
<a name="G-TYPE-IS-DERIVED:CAPS"></a><h3>G_TYPE_IS_DERIVED()</h3>
<pre class="programlisting">#define G_TYPE_IS_DERIVED(type) ((type) &gt; G_TYPE_FUNDAMENTAL_MAX)
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is derived (or in object-oriented terminology:
inherited) from another type (this holds true for all non-fundamental
types).
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_FUNDAMENTAL()">
<a name="G-TYPE-IS-FUNDAMENTAL:CAPS"></a><h3>G_TYPE_IS_FUNDAMENTAL()</h3>
<pre class="programlisting">#define G_TYPE_IS_FUNDAMENTAL(type) ((type) &lt;= G_TYPE_FUNDAMENTAL_MAX)
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is a fundamental type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_VALUE_TYPE()">
<a name="G-TYPE-IS-VALUE-TYPE:CAPS"></a><h3>G_TYPE_IS_VALUE_TYPE()</h3>
<pre class="programlisting">#define G_TYPE_IS_VALUE_TYPE(type) (g_type_check_is_value_type (type))
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is a value type and can be used with <a class="link" href="gobject-Generic-values.html#g-value-init" title="g_value_init ()"><code class="function">g_value_init()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_HAS_VALUE_TABLE()">
<a name="G-TYPE-HAS-VALUE-TABLE:CAPS"></a><h3>G_TYPE_HAS_VALUE_TABLE()</h3>
<pre class="programlisting">#define G_TYPE_HAS_VALUE_TABLE(type) (g_type_value_table_peek (type) != NULL)
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> has a <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_CLASSED()">
<a name="G-TYPE-IS-CLASSED:CAPS"></a><h3>G_TYPE_IS_CLASSED()</h3>
<pre class="programlisting">#define G_TYPE_IS_CLASSED(type) (g_type_test_flags ((type), G_TYPE_FLAG_CLASSED))
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is a classed type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_INSTANTIATABLE()">
<a name="G-TYPE-IS-INSTANTIATABLE:CAPS"></a><h3>G_TYPE_IS_INSTANTIATABLE()</h3>
<pre class="programlisting">#define G_TYPE_IS_INSTANTIATABLE(type) (g_type_test_flags ((type), G_TYPE_FLAG_INSTANTIATABLE))
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> can be instantiated. Instantiation is the
process of creating an instance (object) of this type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_DERIVABLE()">
<a name="G-TYPE-IS-DERIVABLE:CAPS"></a><h3>G_TYPE_IS_DERIVABLE()</h3>
<pre class="programlisting">#define G_TYPE_IS_DERIVABLE(type) (g_type_test_flags ((type), G_TYPE_FLAG_DERIVABLE))
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is a derivable type. A derivable type can
be used as the base class of a flat (single-level) class hierarchy.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_DEEP_DERIVABLE()">
<a name="G-TYPE-IS-DEEP-DERIVABLE:CAPS"></a><h3>G_TYPE_IS_DEEP_DERIVABLE()</h3>
<pre class="programlisting">#define G_TYPE_IS_DEEP_DERIVABLE(type) (g_type_test_flags ((type), G_TYPE_FLAG_DEEP_DERIVABLE))
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is a deep derivable type. A deep derivable type
can be used as the base class of a deep (multi-level) class hierarchy.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_IS_INTERFACE()">
<a name="G-TYPE-IS-INTERFACE:CAPS"></a><h3>G_TYPE_IS_INTERFACE()</h3>
<pre class="programlisting">#define G_TYPE_IS_INTERFACE(type) (G_TYPE_FUNDAMENTAL (type) == G_TYPE_INTERFACE)
</pre>
<p>
Checks if <em class="parameter"><code>type</code></em> is an interface type.
An interface type provides a pure API, the implementation
of which is provided by another type (which is then said to conform
to the interface). GLib interfaces are somewhat analogous to Java
interfaces and C++ classes containing only pure virtual functions,
with the difference that GType interfaces are not derivable (but see
<a class="link" href="gobject-Type-Information.html#g-type-interface-add-prerequisite" title="g_type_interface_add_prerequisite ()"><code class="function">g_type_interface_add_prerequisite()</code></a> for an alternative).
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GTypeInterface">
<a name="GTypeInterface"></a><h3>GTypeInterface</h3>
<pre class="programlisting">typedef struct {
} GTypeInterface;
</pre>
<p>
An opaque structure used as the base of all interface types.
</p>
</div>
<hr>
<div class="refsect2" title="GTypeInstance">
<a name="GTypeInstance"></a><h3>GTypeInstance</h3>
<pre class="programlisting">typedef struct {
} GTypeInstance;
</pre>
<p>
An opaque structure used as the base of all type instances.
</p>
</div>
<hr>
<div class="refsect2" title="GTypeClass">
<a name="GTypeClass"></a><h3>GTypeClass</h3>
<pre class="programlisting">typedef struct {
} GTypeClass;
</pre>
<p>
An opaque structure used as the base of all classes.
</p>
</div>
<hr>
<div class="refsect2" title="GTypeInfo">
<a name="GTypeInfo"></a><h3>GTypeInfo</h3>
<pre class="programlisting">typedef struct {
/* interface types, classed types, instantiated types */
guint16 class_size;
GBaseInitFunc base_init;
GBaseFinalizeFunc base_finalize;
/* interface types, classed types, instantiated types */
GClassInitFunc class_init;
GClassFinalizeFunc class_finalize;
gconstpointer class_data;
/* instantiated types */
guint16 instance_size;
guint16 n_preallocs;
GInstanceInitFunc instance_init;
/* value handling */
const GTypeValueTable *value_table;
} GTypeInfo;
</pre>
<p>
This structure is used to provide the type system with the information
required to initialize and destruct (finalize) a type's class and
its instances.
The initialized structure is passed to the <a class="link" href="gobject-Type-Information.html#g-type-register-static" title="g_type_register_static ()"><code class="function">g_type_register_static()</code></a> function
(or is copied into the provided <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure in the
<a class="link" href="GTypePlugin.html#g-type-plugin-complete-type-info" title="g_type_plugin_complete_type_info ()"><code class="function">g_type_plugin_complete_type_info()</code></a>). The type system will perform a deep
copy of this structure, so its memory does not need to be persistent
across invocation of <a class="link" href="gobject-Type-Information.html#g-type-register-static" title="g_type_register_static ()"><code class="function">g_type_register_static()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#guint16"><span class="type">guint16</span></a> <em class="structfield"><code><a name="GTypeInfo.class-size"></a>class_size</code></em>;</span></p></td>
<td>Size of the class structure (required for interface, classed and instantiatable types).
</td>
</tr>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><span class="type">GBaseInitFunc</span></a> <em class="structfield"><code><a name="GTypeInfo.base-init"></a>base_init</code></em>;</span></p></td>
<td>Location of the base initialization function (optional).
</td>
</tr>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GBaseFinalizeFunc" title="GBaseFinalizeFunc ()"><span class="type">GBaseFinalizeFunc</span></a> <em class="structfield"><code><a name="GTypeInfo.base-finalize"></a>base_finalize</code></em>;</span></p></td>
<td>Location of the base finalization function (optional).
</td>
</tr>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><span class="type">GClassInitFunc</span></a> <em class="structfield"><code><a name="GTypeInfo.class-init"></a>class_init</code></em>;</span></p></td>
<td>Location of the class initialization function for
classed and instantiatable types. Location of the default vtable
inititalization function for interface types. (optional) This function
is used both to fill in virtual functions in the class or default vtable,
and to do type-specific setup such as registering signals and object
properties.
</td>
</tr>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GClassFinalizeFunc" title="GClassFinalizeFunc ()"><span class="type">GClassFinalizeFunc</span></a> <em class="structfield"><code><a name="GTypeInfo.class-finalize"></a>class_finalize</code></em>;</span></p></td>
<td>Location of the class finalization function for
classed and instantiatable types. Location fo the default vtable
finalization function for interface types. (optional)
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#gconstpointer"><span class="type">gconstpointer</span></a> <em class="structfield"><code><a name="GTypeInfo.class-data"></a>class_data</code></em>;</span></p></td>
<td>User-supplied data passed to the class init/finalize functions.
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#guint16"><span class="type">guint16</span></a> <em class="structfield"><code><a name="GTypeInfo.instance-size"></a>instance_size</code></em>;</span></p></td>
<td>Size of the instance (object) structure (required for instantiatable types only).
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#guint16"><span class="type">guint16</span></a> <em class="structfield"><code><a name="GTypeInfo.n-preallocs"></a>n_preallocs</code></em>;</span></p></td>
<td>Prior to GLib 2.10, it specified the number of pre-allocated (cached) instances to reserve memory for (0 indicates no caching). Since GLib 2.10, it is ignored, since instances are allocated with the <a href="./../glib/glib/glib-Memory-Slices.html">slice allocator</a> now.
</td>
</tr>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GInstanceInitFunc" title="GInstanceInitFunc ()"><span class="type">GInstanceInitFunc</span></a> <em class="structfield"><code><a name="GTypeInfo.instance-init"></a>instance_init</code></em>;</span></p></td>
<td>Location of the instance initialization function (optional, for instantiatable types only).
</td>
</tr>
<tr>
<td><p><span class="term">const <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a> *<em class="structfield"><code><a name="GTypeInfo.value-table"></a>value_table</code></em>;</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a> function table for generic handling of GValues of this type (usually only
useful for fundamental types).
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GTypeFundamentalInfo">
<a name="GTypeFundamentalInfo"></a><h3>GTypeFundamentalInfo</h3>
<pre class="programlisting">typedef struct {
GTypeFundamentalFlags type_flags;
} GTypeFundamentalInfo;
</pre>
<p>
A structure that provides information to the type system which is
used specifically for managing fundamental types.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GTypeFundamentalFlags" title="enum GTypeFundamentalFlags"><span class="type">GTypeFundamentalFlags</span></a> <em class="structfield"><code><a name="GTypeFundamentalInfo.type-flags"></a>type_flags</code></em>;</span></p></td>
<td>
<a class="link" href="gobject-Type-Information.html#GTypeFundamentalFlags" title="enum GTypeFundamentalFlags"><span class="type">GTypeFundamentalFlags</span></a> describing the characteristics of the fundamental type
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GInterfaceInfo">
<a name="GInterfaceInfo"></a><h3>GInterfaceInfo</h3>
<pre class="programlisting">typedef struct {
GInterfaceInitFunc interface_init;
GInterfaceFinalizeFunc interface_finalize;
gpointer interface_data;
} GInterfaceInfo;
</pre>
<p>
A structure that provides information to the type system which is
used specifically for managing interface types.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GInterfaceInitFunc" title="GInterfaceInitFunc ()"><span class="type">GInterfaceInitFunc</span></a> <em class="structfield"><code><a name="GInterfaceInfo.interface-init"></a>interface_init</code></em>;</span></p></td>
<td>location of the interface initialization function
</td>
</tr>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GInterfaceFinalizeFunc" title="GInterfaceFinalizeFunc ()"><span class="type">GInterfaceFinalizeFunc</span></a> <em class="structfield"><code><a name="GInterfaceInfo.interface-finalize"></a>interface_finalize</code></em>;</span></p></td>
<td>location of the interface finalization function
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> <em class="structfield"><code><a name="GInterfaceInfo.interface-data"></a>interface_data</code></em>;</span></p></td>
<td>user-supplied data passed to the interface init/finalize functions
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GTypeValueTable">
<a name="GTypeValueTable"></a><h3>GTypeValueTable</h3>
<pre class="programlisting">typedef struct {
void (*value_init) (GValue *value);
void (*value_free) (GValue *value);
void (*value_copy) (const GValue *src_value,
GValue *dest_value);
/* varargs functionality (optional) */
gpointer (*value_peek_pointer) (const GValue *value);
gchar *collect_format;
gchar* (*collect_value) (GValue *value,
guint n_collect_values,
GTypeCValue *collect_values,
guint collect_flags);
gchar *lcopy_format;
gchar* (*lcopy_value) (const GValue *value,
guint n_collect_values,
GTypeCValue *collect_values,
guint collect_flags);
} GTypeValueTable;
</pre>
<p>
The <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a> provides the functions required by the <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a> implementation,
to serve as a container for values of a type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="structfield"><code><a name="GTypeValueTable.value-init"></a>value_init</code></em> ()</span></p></td>
<td>Default initialize <em class="parameter"><code>values</code></em> contents by poking values
directly into the value-&gt;data array. The data array of
the <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a> passed into this function was zero-filled
with <code class="function"><code class="function">memset()</code></code>, so no care has to
be taken to free any
old contents. E.g. for the implementation of a string
value that may never be <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, the implementation might
look like:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup">g_strdup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">""</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="structfield"><code><a name="GTypeValueTable.value-free"></a>value_free</code></em> ()</span></p></td>
<td>Free any old contents that might be left in the
data array of the passed in <em class="parameter"><code>value</code></em>. No resources may
remain allocated through the <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a> contents after
this function returns. E.g. for our above string type:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="comment">// only free strings without a specific flag for static storage</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(!(</span><span class="normal">value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">1</span><span class="symbol">].</span><span class="normal">v_uint </span><span class="symbol">&amp;</span><span class="normal"> G_VALUE_NOCOPY_CONTENTS</span><span class="symbol">))</span>
<span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-Memory-Allocation.html#g-free">g_free</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="structfield"><code><a name="GTypeValueTable.value-copy"></a>value_copy</code></em> ()</span></p></td>
<td>
<em class="parameter"><code>dest_value</code></em> is a <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a> with zero-filled data section
and <em class="parameter"><code>src_value</code></em> is a properly setup <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a> of same or
derived type.
The purpose of this function is to copy the contents of
<em class="parameter"><code>src_value</code></em> into <em class="parameter"><code>dest_value</code></em> in a way, that even after
<em class="parameter"><code>src_value</code></em> has been freed, the contents of <em class="parameter"><code>dest_value</code></em>
remain valid. String type example:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">dest_value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup">g_strdup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">src_value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="structfield"><code><a name="GTypeValueTable.value-peek-pointer"></a>value_peek_pointer</code></em> ()</span></p></td>
<td>If the value contents fit into a pointer, such as objects
or strings, return this pointer, so the caller can peek at
the current contents. To extend on our above string example:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">return</span><span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">;</span></pre></td>
</tr>
</tbody>
</table>
</div>
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *<em class="structfield"><code><a name="GTypeValueTable.collect-format"></a>collect_format</code></em>;</span></p></td>
<td>A string format describing how to collect the contents of
this value bit-by-bit. Each character in the format represents
an argument to be collected, and the characters themselves indicate
the type of the argument. Currently supported arguments are:
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"></span></p></td>
<td><p>
'i' - Integers. passed as collect_values[].v_int.
</p></td>
</tr>
<tr>
<td><p><span class="term"></span></p></td>
<td><p>
'l' - Longs. passed as collect_values[].v_long.
</p></td>
</tr>
<tr>
<td><p><span class="term"></span></p></td>
<td><p>
'd' - Doubles. passed as collect_values[].v_double.
</p></td>
</tr>
<tr>
<td><p><span class="term"></span></p></td>
<td><p>
'p' - Pointers. passed as collect_values[].v_pointer.
</p></td>
</tr>
</tbody>
</table></div>
It should be noted that for variable argument list construction,
ANSI C promotes every type smaller than an integer to an int, and
floats to doubles. So for collection of short int or char, 'i'
needs to be used, and for collection of floats 'd'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="structfield"><code><a name="GTypeValueTable.collect-value"></a>collect_value</code></em> ()</span></p></td>
<td>The <code class="function">collect_value()</code> function is responsible for converting the
values collected from a variable argument list into contents
suitable for storage in a GValue. This function should setup
<em class="parameter"><code>value</code></em> similar to <code class="function">value_init()</code>; e.g. for a string value that
does not allow <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> pointers, it needs to either spew an error,
or do an implicit conversion by storing an empty string.
The <em class="parameter"><code>value</code></em> passed in to this function has a zero-filled data
array, so just like for <code class="function">value_init()</code> it is guaranteed to not
contain any old contents that might need freeing.
<em class="parameter"><code>n_collect_values</code></em> is exactly the string length of <em class="parameter"><code>collect_format</code></em>,
and <em class="parameter"><code>collect_values</code></em> is an array of unions <a class="link" href="gobject-Varargs-Value-Collection.html#GTypeCValue" title="union GTypeCValue"><span class="type">GTypeCValue</span></a> with
length <em class="parameter"><code>n_collect_values</code></em>, containing the collected values
according to <em class="parameter"><code>collect_format</code></em>.
<em class="parameter"><code>collect_flags</code></em> is an argument provided as a hint by the caller.
It may contain the flag <code class="literal">G_VALUE_NOCOPY_CONTENTS</code> indicating,
that the collected value contents may be considered "static"
for the duration of the <em class="parameter"><code>value</code></em> lifetime.
Thus an extra copy of the contents stored in <em class="parameter"><code>collect_values</code></em> is
not required for assignment to <em class="parameter"><code>value</code></em>.
For our above string example, we continue with:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(!</span><span class="normal">collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">)</span>
<span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup">g_strdup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">""</span><span class="symbol">);</span>
<span class="keyword">else</span><span class="normal"> </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">collect_flags </span><span class="symbol">&amp;</span><span class="normal"> G_VALUE_NOCOPY_CONTENTS</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer </span><span class="symbol">=</span><span class="normal"> collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">;</span>
<span class="normal"> </span><span class="comment">// keep a flag for the value_free() implementation to not free this string</span>
<span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">1</span><span class="symbol">].</span><span class="normal">v_uint </span><span class="symbol">=</span><span class="normal"> G_VALUE_NOCOPY_CONTENTS</span><span class="symbol">;</span>
<span class="cbracket">}</span>
<span class="keyword">else</span>
<span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup">g_strdup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">);</span>
<span class="keyword">return</span><span class="normal"> <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">;</span></pre></td>
</tr>
</tbody>
</table>
</div>
It should be noted, that it is generally a bad idea to follow the
<span class="type">G_VALUE_NOCOPY_CONTENTS</span> hint for reference counted types. Due to
reentrancy requirements and reference count assertions performed
by the <span class="type">GSignal</span> code, reference counts should always be incremented
for reference counted contents stored in the value-&gt;data array.
To deviate from our string example for a moment, and taking a look
at an exemplary implementation for <code class="function">collect_value()</code> of <a class="link" href="gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a>:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> <a href="gobject-The-Base-Object-Type.html#GObject">GObject</a> </span><span class="symbol">*</span><span class="normal">object </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="gobject-The-Base-Object-Type.html#G-OBJECT:CAPS">G_OBJECT</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">);</span>
<span class="normal"> </span><span class="comment">// never honour G_VALUE_NOCOPY_CONTENTS for ref-counted types</span>
<span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="gobject-The-Base-Object-Type.html#g-object-ref">g_object_ref</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">object</span><span class="symbol">);</span>
<span class="normal"> </span><span class="keyword">return</span><span class="normal"> <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">;</span>
<span class="cbracket">}</span>
<span class="keyword">else</span>
<span class="normal"> </span><span class="keyword">return</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup-printf">g_strdup_printf</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Object passed as invalid NULL pointer"</span><span class="symbol">);</span>
<span class="cbracket">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
The reference count for valid objects is always incremented,
regardless of <em class="parameter"><code>collect_flags</code></em>. For invalid objects, the example
returns a newly allocated string without altering <em class="parameter"><code>value</code></em>.
Upon success, <code class="function">collect_value()</code> needs to return <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>. If, however,
an error condition occurred, <code class="function">collect_value()</code> may spew an
error by returning a newly allocated non-<a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> string, giving
a suitable description of the error condition.
The calling code makes no assumptions about the <em class="parameter"><code>value</code></em>
contents being valid upon error returns, <em class="parameter"><code>value</code></em>
is simply thrown away without further freeing. As such, it is
a good idea to not allocate <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a> contents, prior to returning
an error, however, <code class="function">collect_values()</code> is not obliged to return
a correctly setup <em class="parameter"><code>value</code></em> for error returns, simply because
any non-<a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> return is considered a fatal condition so further
program behaviour is undefined.
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *<em class="structfield"><code><a name="GTypeValueTable.lcopy-format"></a>lcopy_format</code></em>;</span></p></td>
<td>Format description of the arguments to collect for <em class="parameter"><code>lcopy_value</code></em>,
analogous to <em class="parameter"><code>collect_format</code></em>. Usually, <em class="parameter"><code>lcopy_format</code></em> string consists
only of 'p's to provide <code class="function">lcopy_value()</code> with pointers to storage locations.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="structfield"><code><a name="GTypeValueTable.lcopy-value"></a>lcopy_value</code></em> ()</span></p></td>
<td>This function is responsible for storing the <em class="parameter"><code>value</code></em> contents into
arguments passed through a variable argument list which got
collected into <em class="parameter"><code>collect_values</code></em> according to <em class="parameter"><code>lcopy_format</code></em>.
<em class="parameter"><code>n_collect_values</code></em> equals the string length of <em class="parameter"><code>lcopy_format</code></em>,
and <em class="parameter"><code>collect_flags</code></em> may contain <code class="literal">G_VALUE_NOCOPY_CONTENTS</code>.
In contrast to <code class="function">collect_value()</code>, <code class="function">lcopy_value()</code> is obliged to
always properly support <code class="literal">G_VALUE_NOCOPY_CONTENTS</code>.
Similar to <code class="function">collect_value()</code> the function may prematurely abort
by returning a newly allocated string describing an error condition.
To complete the string example:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal"><a href="./../glib/glib/glib-Basic-Types.html#gchar">gchar</a> </span><span class="symbol">**</span><span class="normal">string_p </span><span class="symbol">=</span><span class="normal"> collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">;</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(!</span><span class="normal">string_p</span><span class="symbol">)</span>
<span class="normal"> </span><span class="keyword">return</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup-printf">g_strdup_printf</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"string location passed as NULL"</span><span class="symbol">);</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">collect_flags </span><span class="symbol">&amp;</span><span class="normal"> G_VALUE_NOCOPY_CONTENTS</span><span class="symbol">)</span>
<span class="normal"> </span><span class="symbol">*</span><span class="normal">string_p </span><span class="symbol">=</span><span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">;</span>
<span class="keyword">else</span>
<span class="normal"> </span><span class="symbol">*</span><span class="normal">string_p </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup">g_strdup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
And an illustrative version of <code class="function">lcopy_value()</code> for
reference-counted types:
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal"><a href="gobject-The-Base-Object-Type.html#GObject">GObject</a> </span><span class="symbol">**</span><span class="normal">object_p </span><span class="symbol">=</span><span class="normal"> collect_values</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">;</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(!</span><span class="normal">object_p</span><span class="symbol">)</span>
<span class="normal"> </span><span class="keyword">return</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup-printf">g_strdup_printf</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"object location passed as NULL"</span><span class="symbol">);</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(!</span><span class="normal">value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">)</span>
<span class="normal"> </span><span class="symbol">*</span><span class="normal">object_p </span><span class="symbol">=</span><span class="normal"> <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">;</span>
<span class="keyword">else</span><span class="normal"> </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">collect_flags </span><span class="symbol">&amp;</span><span class="normal"> G_VALUE_NOCOPY_CONTENTS</span><span class="symbol">)</span><span class="normal"> </span><span class="comment">// always honour</span>
<span class="normal"> </span><span class="symbol">*</span><span class="normal">object_p </span><span class="symbol">=</span><span class="normal"> value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">;</span>
<span class="keyword">else</span>
<span class="normal"> </span><span class="symbol">*</span><span class="normal">object_p </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="gobject-The-Base-Object-Type.html#g-object-ref">g_object_ref</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">value</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">[</span><span class="number">0</span><span class="symbol">].</span><span class="normal">v_pointer</span><span class="symbol">);</span>
<span class="keyword">return</span><span class="normal"> <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">;</span></pre></td>
</tr>
</tbody>
</table>
</div>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FROM_INSTANCE()">
<a name="G-TYPE-FROM-INSTANCE:CAPS"></a><h3>G_TYPE_FROM_INSTANCE()</h3>
<pre class="programlisting">#define G_TYPE_FROM_INSTANCE(instance) (G_TYPE_FROM_CLASS (((GTypeInstance*) (instance))-&gt;g_class))
</pre>
<p>
Get the type identifier from a given <em class="parameter"><code>instance</code></em> structure.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>Location of a valid <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FROM_CLASS()">
<a name="G-TYPE-FROM-CLASS:CAPS"></a><h3>G_TYPE_FROM_CLASS()</h3>
<pre class="programlisting">#define G_TYPE_FROM_CLASS(g_class) (((GTypeClass*) (g_class))-&gt;g_type)
</pre>
<p>
Get the type identifier from a given <em class="parameter"><code>class</code></em> structure.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>Location of a valid <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FROM_INTERFACE()">
<a name="G-TYPE-FROM-INTERFACE:CAPS"></a><h3>G_TYPE_FROM_INTERFACE()</h3>
<pre class="programlisting">#define G_TYPE_FROM_INTERFACE(g_iface) (((GTypeInterface*) (g_iface))-&gt;g_type)
</pre>
<p>
Get the type identifier from a given <em class="parameter"><code>interface</code></em> structure.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_iface</code></em> :</span></p></td>
<td>Location of a valid <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INSTANCE_GET_CLASS()">
<a name="G-TYPE-INSTANCE-GET-CLASS:CAPS"></a><h3>G_TYPE_INSTANCE_GET_CLASS()</h3>
<pre class="programlisting">#define G_TYPE_INSTANCE_GET_CLASS(instance, g_type, c_type) (_G_TYPE_IGC ((instance), (g_type), c_type))
</pre>
<p>
Get the class structure of a given <em class="parameter"><code>instance</code></em>, casted
to a specified ancestor type <em class="parameter"><code>g_type</code></em> of the instance.
</p>
<p>
Note that while calling a <a class="link" href="gobject-Type-Information.html#GInstanceInitFunc" title="GInstanceInitFunc ()"><code class="function">GInstanceInitFunc()</code></a>, the class pointer gets
modified, so it might not always return the expected pointer.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>Location of the <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the class to be returned.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>c_type</code></em> :</span></p></td>
<td>The C type of the class structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> a pointer to the class structure
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INSTANCE_GET_INTERFACE()">
<a name="G-TYPE-INSTANCE-GET-INTERFACE:CAPS"></a><h3>G_TYPE_INSTANCE_GET_INTERFACE()</h3>
<pre class="programlisting">#define G_TYPE_INSTANCE_GET_INTERFACE(instance, g_type, c_type) (_G_TYPE_IGI ((instance), (g_type), c_type))
</pre>
<p>
Get the interface structure for interface <em class="parameter"><code>g_type</code></em> of a given <em class="parameter"><code>instance</code></em>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>Location of the <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the interface to be returned.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>c_type</code></em> :</span></p></td>
<td>The C type of the interface structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> a pointer to the interface structure
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INSTANCE_GET_PRIVATE()">
<a name="G-TYPE-INSTANCE-GET-PRIVATE:CAPS"></a><h3>G_TYPE_INSTANCE_GET_PRIVATE()</h3>
<pre class="programlisting">#define G_TYPE_INSTANCE_GET_PRIVATE(instance, g_type, c_type) ((c_type*) g_type_instance_get_private ((GTypeInstance*) (instance), (g_type)))
</pre>
<p>
Gets the private structure for a particular type.
The private structure must have been registered in the
class_init function with <a class="link" href="gobject-Type-Information.html#g-type-class-add-private" title="g_type_class_add_private ()"><code class="function">g_type_class_add_private()</code></a>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>the instance of a type deriving from <em class="parameter"><code>private_type</code></em>.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>the type identifying which private data to retrieve.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>c_type</code></em> :</span></p></td>
<td>The C type for the private structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> a pointer to the private data structure.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_INSTANCE()">
<a name="G-TYPE-CHECK-INSTANCE:CAPS"></a><h3>G_TYPE_CHECK_INSTANCE()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_INSTANCE(instance) (_G_TYPE_CHI ((GTypeInstance*) (instance)))
</pre>
<p>
Checks if <em class="parameter"><code>instance</code></em> is a valid <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure,
otherwise issues a warning and returns <a href="./../glib/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>Location of a <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_INSTANCE_CAST()">
<a name="G-TYPE-CHECK-INSTANCE-CAST:CAPS"></a><h3>G_TYPE_CHECK_INSTANCE_CAST()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_INSTANCE_CAST(instance, g_type, c_type) (_G_TYPE_CIC ((instance), (g_type), c_type))
</pre>
<p>
Checks that <em class="parameter"><code>instance</code></em> is an instance of the type identified by <em class="parameter"><code>g_type</code></em>
and issues a warning if this is not the case. Returns <em class="parameter"><code>instance</code></em> casted
to a pointer to <em class="parameter"><code>c_type</code></em>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>Location of a <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The type to be returned.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>c_type</code></em> :</span></p></td>
<td>The corresponding C type of <em class="parameter"><code>g_type</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_INSTANCE_TYPE()">
<a name="G-TYPE-CHECK-INSTANCE-TYPE:CAPS"></a><h3>G_TYPE_CHECK_INSTANCE_TYPE()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_INSTANCE_TYPE(instance, g_type) (_G_TYPE_CIT ((instance), (g_type)))
</pre>
<p>
Checks if <em class="parameter"><code>instance</code></em> is an instance of the type identified by <em class="parameter"><code>g_type</code></em>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>Location of a <a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The type to be checked
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_CLASS_CAST()">
<a name="G-TYPE-CHECK-CLASS-CAST:CAPS"></a><h3>G_TYPE_CHECK_CLASS_CAST()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_CLASS_CAST(g_class, g_type, c_type) (_G_TYPE_CCC ((g_class), (g_type), c_type))
</pre>
<p>
Checks that <em class="parameter"><code>g_class</code></em> is a class structure of the type identified by <em class="parameter"><code>g_type</code></em>
and issues a warning if this is not the case. Returns <em class="parameter"><code>g_class</code></em> casted
to a pointer to <em class="parameter"><code>c_type</code></em>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>Location of a <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The type to be returned.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>c_type</code></em> :</span></p></td>
<td>The corresponding C type of class structure of <em class="parameter"><code>g_type</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_CLASS_TYPE()">
<a name="G-TYPE-CHECK-CLASS-TYPE:CAPS"></a><h3>G_TYPE_CHECK_CLASS_TYPE()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_CLASS_TYPE(g_class, g_type) (_G_TYPE_CCT ((g_class), (g_type)))
</pre>
<p>
Checks if <em class="parameter"><code>g_class</code></em> is a class structure of the type identified by
<em class="parameter"><code>g_type</code></em>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>Location of a <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The type to be checked.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_VALUE()">
<a name="G-TYPE-CHECK-VALUE:CAPS"></a><h3>G_TYPE_CHECK_VALUE()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_VALUE(value) (_G_TYPE_CHV ((value)))
</pre>
<p>
Checks if <em class="parameter"><code>value</code></em> has been initialized to hold values
of a value type.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>value</code></em> :</span></p></td>
<td>a <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHECK_VALUE_TYPE()">
<a name="G-TYPE-CHECK-VALUE-TYPE:CAPS"></a><h3>G_TYPE_CHECK_VALUE_TYPE()</h3>
<pre class="programlisting">#define G_TYPE_CHECK_VALUE_TYPE(value, g_type) (_G_TYPE_CVH ((value), (g_type)))
</pre>
<p>
Checks if <em class="parameter"><code>value</code></em> has been initialized to hold values
of type <em class="parameter"><code>g_type</code></em>.
</p>
<p>
This macro should only be used in type implementations.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>value</code></em> :</span></p></td>
<td>a <a class="link" href="gobject-Generic-values.html#GValue" title="GValue"><span class="type">GValue</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>The type to be checked.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FLAG_RESERVED_ID_BIT">
<a name="G-TYPE-FLAG-RESERVED-ID-BIT:CAPS"></a><h3>G_TYPE_FLAG_RESERVED_ID_BIT</h3>
<pre class="programlisting">#define G_TYPE_FLAG_RESERVED_ID_BIT ((GType) (1 &lt;&lt; 0))
</pre>
<p>
A bit in the type number that's supposed to be left untouched.
</p>
</div>
<hr>
<div class="refsect2" title="g_type_init ()">
<a name="g-type-init"></a><h3>g_type_init ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_init (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>
Prior to any use of the type system, <a class="link" href="gobject-Type-Information.html#g-type-init" title="g_type_init ()"><code class="function">g_type_init()</code></a> has to be called
to initialize the type system and assorted other code portions
(such as the various fundamental type implementations or the signal
system).
</p>
<p>
Since version 2.24 this also initializes the thread system
</p>
</div>
<hr>
<div class="refsect2" title="enum GTypeDebugFlags">
<a name="GTypeDebugFlags"></a><h3>enum GTypeDebugFlags</h3>
<pre class="programlisting">typedef enum /*&lt; skip &gt;*/
{
G_TYPE_DEBUG_NONE = 0,
G_TYPE_DEBUG_OBJECTS = 1 &lt;&lt; 0,
G_TYPE_DEBUG_SIGNALS = 1 &lt;&lt; 1,
G_TYPE_DEBUG_MASK = 0x03
} GTypeDebugFlags;
</pre>
<p>
The <span class="type">GTypeDebugFlags</span> enumeration values can be passed to
<a class="link" href="gobject-Type-Information.html#g-type-init-with-debug-flags" title="g_type_init_with_debug_flags ()"><code class="function">g_type_init_with_debug_flags()</code></a> to trigger debugging messages during runtime.
Note that the messages can also be triggered by setting the
<code class="envar">GOBJECT_DEBUG</code> environment variable to a ':'-separated list of
"objects" and "signals".
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><a name="G-TYPE-DEBUG-NONE:CAPS"></a><span class="term"><code class="literal">G_TYPE_DEBUG_NONE</code></span></p></td>
<td>Print no messages.
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-DEBUG-OBJECTS:CAPS"></a><span class="term"><code class="literal">G_TYPE_DEBUG_OBJECTS</code></span></p></td>
<td>Print messages about object bookkeeping.
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-DEBUG-SIGNALS:CAPS"></a><span class="term"><code class="literal">G_TYPE_DEBUG_SIGNALS</code></span></p></td>
<td>Print messages about signal emissions.
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-DEBUG-MASK:CAPS"></a><span class="term"><code class="literal">G_TYPE_DEBUG_MASK</code></span></p></td>
<td>Mask covering all debug flags.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_init_with_debug_flags ()">
<a name="g-type-init-with-debug-flags"></a><h3>g_type_init_with_debug_flags ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_init_with_debug_flags (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeDebugFlags" title="enum GTypeDebugFlags"><span class="type">GTypeDebugFlags</span></a> debug_flags</code></em>);</pre>
<p>
Similar to <a class="link" href="gobject-Type-Information.html#g-type-init" title="g_type_init ()"><code class="function">g_type_init()</code></a>, but additionally sets debug flags.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>debug_flags</code></em> :</span></p></td>
<td>Bitwise combination of <a class="link" href="gobject-Type-Information.html#GTypeDebugFlags" title="enum GTypeDebugFlags"><span class="type">GTypeDebugFlags</span></a> values for
debugging purposes.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_name ()">
<a name="g-type-name"></a><h3>g_type_name ()</h3>
<pre class="programlisting">const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="returnvalue">gchar</span></a>* g_type_name (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Get the unique name that is assigned to a type ID. Note that this
function (like all other GType API) cannot cope with invalid type
IDs. <a class="link" href="gobject-Type-Information.html#G-TYPE-INVALID:CAPS" title="G_TYPE_INVALID"><code class="literal">G_TYPE_INVALID</code></a> may be passed to this function, as may be any
other validly registered type ID, but randomized type IDs should
not be passed in and will most likely lead to a crash.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>Type to return name for.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> Static type name or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_qname ()">
<a name="g-type-qname"></a><h3>g_type_qname ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="returnvalue">GQuark</span></a> g_type_qname (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Get the corresponding quark of the type IDs name.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>Type to return quark of type name for.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The type names quark or 0.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_from_name ()">
<a name="g-type-from-name"></a><h3>g_type_from_name ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_from_name (<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *name</code></em>);</pre>
<p>
Lookup the type ID from a given type name, returning 0 if no type
has been registered under this name (this is the preferred method
to find out by name whether a specific type has been registered
yet).
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>name</code></em> :</span></p></td>
<td>Type name to lookup.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> Corresponding type ID or 0.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_parent ()">
<a name="g-type-parent"></a><h3>g_type_parent ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_parent (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Return the direct parent type of the passed in type. If the passed
in type has no parent, i.e. is a fundamental type, 0 is returned.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>The derived type.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The parent type.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_depth ()">
<a name="g-type-depth"></a><h3>g_type_depth ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="returnvalue">guint</span></a> g_type_depth (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Returns the length of the ancestry of the passed in type. This
includes the type itself, so that e.g. a fundamental type has depth 1.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The depth of <em class="parameter"><code>type</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_next_base ()">
<a name="g-type-next-base"></a><h3>g_type_next_base ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_next_base (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> leaf_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> root_type</code></em>);</pre>
<p>
Given a <em class="parameter"><code>leaf_type</code></em> and a <em class="parameter"><code>root_type</code></em> which is contained in its
anchestry, return the type that <em class="parameter"><code>root_type</code></em> is the immediate parent
of. In other words, this function determines the type that is
derived directly from <em class="parameter"><code>root_type</code></em> which is also a base class of
<em class="parameter"><code>leaf_type</code></em>. Given a root type and a leaf type, this function can
be used to determine the types and order in which the leaf type is
descended from the root type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>leaf_type</code></em> :</span></p></td>
<td>Descendant of <em class="parameter"><code>root_type</code></em> and the type to be returned.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>root_type</code></em> :</span></p></td>
<td>Immediate parent of the returned type.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> Immediate child of <em class="parameter"><code>root_type</code></em> and anchestor of <em class="parameter"><code>leaf_type</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_is_a ()">
<a name="g-type-is-a"></a><h3>g_type_is_a ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> g_type_is_a (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> is_a_type</code></em>);</pre>
<p>
If <em class="parameter"><code>is_a_type</code></em> is a derivable type, check whether <em class="parameter"><code>type</code></em> is a
descendant of <em class="parameter"><code>is_a_type</code></em>. If <em class="parameter"><code>is_a_type</code></em> is an interface, check
whether <em class="parameter"><code>type</code></em> conforms to it.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>Type to check anchestry for.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>is_a_type</code></em> :</span></p></td>
<td>Possible anchestor of <em class="parameter"><code>type</code></em> or interface <em class="parameter"><code>type</code></em> could conform to.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if <em class="parameter"><code>type</code></em> is_a <em class="parameter"><code>is_a_type</code></em> holds true.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_class_ref ()">
<a name="g-type-class-ref"></a><h3>g_type_class_ref ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_class_ref (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Increments the reference count of the class structure belonging to
<em class="parameter"><code>type</code></em>. This function will demand-create the class if it doesn't
exist already.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>Type ID of a classed type.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure for the given type ID.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_class_peek ()">
<a name="g-type-class-peek"></a><h3>g_type_class_peek ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_class_peek (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
This function is essentially the same as <a class="link" href="gobject-Type-Information.html#g-type-class-ref" title="g_type_class_ref ()"><code class="function">g_type_class_ref()</code></a>, except that
the classes reference count isn't incremented. As a consequence, this function
may return <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if the class of the type passed in does not currently
exist (hasn't been referenced before).
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>Type ID of a classed type.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure for the given type ID or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
if the class does not currently exist.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_class_peek_static ()">
<a name="g-type-class-peek-static"></a><h3>g_type_class_peek_static ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_class_peek_static (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
A more efficient version of <a class="link" href="gobject-Type-Information.html#g-type-class-peek" title="g_type_class_peek ()"><code class="function">g_type_class_peek()</code></a> which works only for
static types.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>Type ID of a classed type.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure for the given type ID or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
if the class does not currently exist or is dynamically loaded.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_class_unref ()">
<a name="g-type-class-unref"></a><h3>g_type_class_unref ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_class_unref (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);</pre>
<p>
Decrements the reference count of the class structure being passed in.
Once the last reference count of a class has been released, classes
may be finalized by the type system, so further dereferencing of a
class pointer after <a class="link" href="gobject-Type-Information.html#g-type-class-unref" title="g_type_class_unref ()"><code class="function">g_type_class_unref()</code></a> are invalid.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to unreference.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_class_peek_parent ()">
<a name="g-type-class-peek-parent"></a><h3>g_type_class_peek_parent ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_class_peek_parent (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);</pre>
<p>
This is a convenience function often needed in class initializers.
It returns the class structure of the immediate parent type of the
class passed in. Since derived classes hold a reference count on
their parent classes as long as they are instantiated, the returned
class will always exist. This function is essentially equivalent
to:
</p>
<p>
</p>
<pre class="programlisting">
g_type_class_peek (g_type_parent (G_TYPE_FROM_CLASS (g_class)));
</pre>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to retrieve the parent class for.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The parent class of <em class="parameter"><code>g_class</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_class_add_private ()">
<a name="g-type-class-add-private"></a><h3>g_type_class_add_private ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_class_add_private (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gsize"><span class="type">gsize</span></a> private_size</code></em>);</pre>
<p>
Registers a private structure for an instantiatable type;
when an object is allocated, the private structures for
the type and all of its parent types are allocated
sequentially in the same memory block as the public
structures. This function should be called in the
type's <code class="function">class_init()</code> function. The private structure can
be retrieved using the <a class="link" href="gobject-Type-Information.html#G-TYPE-INSTANCE-GET-PRIVATE:CAPS" title="G_TYPE_INSTANCE_GET_PRIVATE()"><code class="function">G_TYPE_INSTANCE_GET_PRIVATE()</code></a> macro.
The following example shows attaching a private structure
<span class="structname">MyObjectPrivate</span> to an object
<span class="structname">MyObject</span> defined in the standard GObject
fashion.
type's <code class="function">class_init()</code> function.
</p>
<p>
</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
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<td class="listing_code"><pre class="programlisting"><span class="keyword">typedef</span><span class="normal"> </span><span class="keyword">struct</span><span class="normal"> </span><span class="classname">_MyObject</span><span class="normal"> MyObject</span><span class="symbol">;</span>
<span class="keyword">typedef</span><span class="normal"> </span><span class="keyword">struct</span><span class="normal"> </span><span class="classname">_MyObjectPrivate</span><span class="normal"> MyObjectPrivate</span><span class="symbol">;</span>
<span class="keyword">struct</span><span class="normal"> </span><span class="classname">_MyObject</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> <a href="gobject-The-Base-Object-Type.html#GObject">GObject</a> parent</span><span class="symbol">;</span>
<span class="normal"> MyObjectPrivate </span><span class="symbol">*</span><span class="normal">priv</span><span class="symbol">;</span>
<span class="cbracket">}</span><span class="symbol">;</span>
<span class="keyword">struct</span><span class="normal"> </span><span class="classname">_MyObjectPrivate</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="type">int</span><span class="normal"> some_field</span><span class="symbol">;</span>
<span class="cbracket">}</span><span class="symbol">;</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">my_object_class_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">MyObjectClass </span><span class="symbol">*</span><span class="normal">klass</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="gobject-Type-Information.html#g-type-class-add-private">g_type_class_add_private</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">klass</span><span class="symbol">,</span><span class="normal"> </span><span class="keyword">sizeof</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">MyObjectPrivate</span><span class="symbol">));</span>
<span class="cbracket">}</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">my_object_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">MyObject </span><span class="symbol">*</span><span class="normal">my_object</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> my_object</span><span class="symbol">-&gt;</span><span class="normal">priv </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="gobject-Type-Information.html#G-TYPE-INSTANCE-GET-PRIVATE:CAPS">G_TYPE_INSTANCE_GET_PRIVATE</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">my_object</span><span class="symbol">,</span>
<span class="normal"> MY_TYPE_OBJECT</span><span class="symbol">,</span>
<span class="normal"> MyObjectPrivate</span><span class="symbol">);</span>
<span class="cbracket">}</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">int</span>
<span class="function">my_object_get_some_field</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">MyObject </span><span class="symbol">*</span><span class="normal">my_object</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> MyObjectPrivate </span><span class="symbol">*</span><span class="normal">priv </span><span class="symbol">=</span><span class="normal"> my_object</span><span class="symbol">-&gt;</span><span class="normal">priv</span><span class="symbol">;</span>
<span class="normal"> </span><span class="keyword">return</span><span class="normal"> priv</span><span class="symbol">-&gt;</span><span class="normal">some_field</span><span class="symbol">;</span>
<span class="cbracket">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>class structure for an instantiatable type
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>private_size</code></em> :</span></p></td>
<td>size of private structure.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_add_class_private ()">
<a name="g-type-add-class-private"></a><h3>g_type_add_class_private ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_add_class_private (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> class_type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gsize"><span class="type">gsize</span></a> private_size</code></em>);</pre>
<p>
Registers a private class structure for a classed type;
when the class is allocated, the private structures for
the class and all of its parent types are allocated
sequentially in the same memory block as the public
structures. This function should be called in the
type's <code class="function">get_type()</code> function after the type is registered.
The private structure can be retrieved using the
<code class="function">G_TYPE_CLASS_GET_PRIVATE()</code> macro.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>class_type</code></em> :</span></p></td>
<td>GType of an classed type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>private_size</code></em> :</span></p></td>
<td>size of private structure.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.24</p>
</div>
<hr>
<div class="refsect2" title="g_type_interface_peek ()">
<a name="g-type-interface-peek"></a><h3>g_type_interface_peek ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_interface_peek (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> instance_class</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> iface_type</code></em>);</pre>
<p>
Returns the <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> structure of an interface to which the
passed in class conforms.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance_class</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>iface_type</code></em> :</span></p></td>
<td>An interface ID which this class conforms to.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The GTypeInterface structure of iface_type if implemented
by <em class="parameter"><code>instance_class</code></em>, <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> otherwise
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_interface_peek_parent ()">
<a name="g-type-interface-peek-parent"></a><h3>g_type_interface_peek_parent ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_interface_peek_parent (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>);</pre>
<p>
Returns the corresponding <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> structure of the parent type
of the instance type to which <em class="parameter"><code>g_iface</code></em> belongs. This is useful when
deriving the implementation of an interface from the parent type and
then possibly overriding some methods.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_iface</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> structure.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The corresponding <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> structure of the parent
type of the instance type to which <em class="parameter"><code>g_iface</code></em> belongs, or
<a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if the parent type doesn't conform to the interface.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_default_interface_ref ()">
<a name="g-type-default-interface-ref"></a><h3>g_type_default_interface_ref ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_default_interface_ref (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> g_type</code></em>);</pre>
<p>
Increments the reference count for the interface type <em class="parameter"><code>g_type</code></em>,
and returns the default interface vtable for the type.
</p>
<p>
If the type is not currently in use, then the default vtable
for the type will be created and initalized by calling
the base interface init and default vtable init functions for
the type (the @<em class="structfield"><code>base_init</code></em>
and <em class="structfield"><code>class_init</code></em> members of <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>).
Calling <a class="link" href="gobject-Type-Information.html#g-type-default-interface-ref" title="g_type_default_interface_ref ()"><code class="function">g_type_default_interface_ref()</code></a> is useful when you
want to make sure that signals and properties for an interface
have been installed.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>an interface type
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the default vtable for the interface; call
<a class="link" href="gobject-Type-Information.html#g-type-default-interface-unref" title="g_type_default_interface_unref ()"><code class="function">g_type_default_interface_unref()</code></a> when you are done using
the interface.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_default_interface_peek ()">
<a name="g-type-default-interface-peek"></a><h3>g_type_default_interface_peek ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_default_interface_peek (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> g_type</code></em>);</pre>
<p>
If the interface type <em class="parameter"><code>g_type</code></em> is currently in use, returns its
default interface vtable.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_type</code></em> :</span></p></td>
<td>an interface type
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the default vtable for the interface, or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
if the type is not currently in use.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_default_interface_unref ()">
<a name="g-type-default-interface-unref"></a><h3>g_type_default_interface_unref ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_default_interface_unref (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>);</pre>
<p>
Decrements the reference count for the type corresponding to the
interface default vtable <em class="parameter"><code>g_iface</code></em>. If the type is dynamic, then
when no one is using the interface and all references have
been released, the finalize function for the interface's default
vtable (the <em class="structfield"><code>class_finalize</code></em> member of
<a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>) will be called.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>g_iface</code></em> :</span></p></td>
<td>the default vtable structure for a interface, as
returned by <a class="link" href="gobject-Type-Information.html#g-type-default-interface-ref" title="g_type_default_interface_ref ()"><code class="function">g_type_default_interface_ref()</code></a>
</td>
</tr></tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_children ()">
<a name="g-type-children"></a><h3>g_type_children ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a>* g_type_children (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> *n_children</code></em>);</pre>
<p>
Return a newly allocated and 0-terminated array of type IDs, listing the
child types of <em class="parameter"><code>type</code></em>. The return value has to be <a href="./../glib/glib/glib-Memory-Allocation.html#g-free"><code class="function">g_free()</code></a>ed after use.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>The parent type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_children</code></em> :</span></p></td>
<td>Optional <a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> pointer to contain the number of child types.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> Newly allocated and 0-terminated array of child types.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_interfaces ()">
<a name="g-type-interfaces"></a><h3>g_type_interfaces ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a>* g_type_interfaces (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> *n_interfaces</code></em>);</pre>
<p>
Return a newly allocated and 0-terminated array of type IDs, listing the
interface types that <em class="parameter"><code>type</code></em> conforms to. The return value has to be
<a href="./../glib/glib/glib-Memory-Allocation.html#g-free"><code class="function">g_free()</code></a>ed after use.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>The type to list interface types for.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_interfaces</code></em> :</span></p></td>
<td>Optional <a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> pointer to contain the number of
interface types.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> Newly allocated and 0-terminated array of interface types.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_interface_prerequisites ()">
<a name="g-type-interface-prerequisites"></a><h3>g_type_interface_prerequisites ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a>* g_type_interface_prerequisites (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> *n_prerequisites</code></em>);</pre>
<p>
Returns the prerequisites of an interfaces type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>interface_type</code></em> :</span></p></td>
<td>an interface type
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_prerequisites</code></em> :</span></p></td>
<td>location to return the number of prerequisites, or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> a newly-allocated zero-terminated array of <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> containing
the prerequisites of <em class="parameter"><code>interface_type</code></em>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.2</p>
</div>
<hr>
<div class="refsect2" title="g_type_set_qdata ()">
<a name="g-type-set-qdata"></a><h3>g_type_set_qdata ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_set_qdata (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> quark</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> data</code></em>);</pre>
<p>
Attaches arbitrary data to a type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>a <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>quark</code></em> :</span></p></td>
<td>a <a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> id to identify the data
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>data</code></em> :</span></p></td>
<td>the data
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_get_qdata ()">
<a name="g-type-get-qdata"></a><h3>g_type_get_qdata ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="returnvalue">gpointer</span></a> g_type_get_qdata (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> quark</code></em>);</pre>
<p>
Obtains data which has previously been attached to <em class="parameter"><code>type</code></em>
with <a class="link" href="gobject-Type-Information.html#g-type-set-qdata" title="g_type_set_qdata ()"><code class="function">g_type_set_qdata()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>a <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>quark</code></em> :</span></p></td>
<td>a <a href="./../glib/glib/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> id to identify the data
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the data, or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if no data was found
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_query ()">
<a name="g-type-query"></a><h3>g_type_query ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_query (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeQuery" title="GTypeQuery"><span class="type">GTypeQuery</span></a> *query</code></em>);</pre>
<p>
Queries the type system for information about a specific type.
This function will fill in a user-provided structure to hold
type-specific information. If an invalid <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> is passed in, the
<em class="parameter"><code>type</code></em> member of the <a class="link" href="gobject-Type-Information.html#GTypeQuery" title="GTypeQuery"><span class="type">GTypeQuery</span></a> is 0. All members filled into the
<a class="link" href="gobject-Type-Information.html#GTypeQuery" title="GTypeQuery"><span class="type">GTypeQuery</span></a> structure should be considered constant and have to be
left untouched.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of a static, classed type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>query</code></em> :</span></p></td>
<td>A user provided structure that is filled in with constant values
upon success.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GTypeQuery">
<a name="GTypeQuery"></a><h3>GTypeQuery</h3>
<pre class="programlisting">typedef struct {
GType type;
const gchar *type_name;
guint class_size;
guint instance_size;
} GTypeQuery;
</pre>
<p>
A structure holding information for a specific type. It is
filled in by the <a class="link" href="gobject-Type-Information.html#g-type-query" title="g_type_query ()"><code class="function">g_type_query()</code></a> function.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> <em class="structfield"><code><a name="GTypeQuery.type"></a>type</code></em>;</span></p></td>
<td>the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of the type.
</td>
</tr>
<tr>
<td><p><span class="term">const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *<em class="structfield"><code><a name="GTypeQuery.type-name"></a>type_name</code></em>;</span></p></td>
<td>the name of the type.
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> <em class="structfield"><code><a name="GTypeQuery.class-size"></a>class_size</code></em>;</span></p></td>
<td>the size of the class structure.
</td>
</tr>
<tr>
<td><p><span class="term"><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> <em class="structfield"><code><a name="GTypeQuery.instance-size"></a>instance_size</code></em>;</span></p></td>
<td>the size of the instance structure.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GBaseInitFunc ()">
<a name="GBaseInitFunc"></a><h3>GBaseInitFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GBaseInitFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);</pre>
<p>
A callback function used by the type system to do base initialization
of the class structures of derived types. It is called as part of the
initialization process of all derived classes and should reallocate
or reset all dynamic class members copied over from the parent class.
For example, class members (such as strings) that are not sufficiently
handled by a plain memory copy of the parent class into the derived class
have to be altered. See <a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><code class="function">GClassInitFunc()</code></a> for a discussion of the class
intialization process.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to initialize.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GBaseFinalizeFunc ()">
<a name="GBaseFinalizeFunc"></a><h3>GBaseFinalizeFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GBaseFinalizeFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);</pre>
<p>
A callback function used by the type system to finalize those portions
of a derived types class structure that were setup from the corresponding
<a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> function. Class finalization basically works the inverse
way in which class intialization is performed.
See <a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><code class="function">GClassInitFunc()</code></a> for a discussion of the class intialization process.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to finalize.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GClassInitFunc ()">
<a name="GClassInitFunc"></a><h3>GClassInitFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GClassInitFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> class_data</code></em>);</pre>
<p>
A callback function used by the type system to initialize the class
of a specific type. This function should initialize all static class
members.
The initialization process of a class involves:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem"><p>
1 - Copying common members from the parent class over to the
derived class structure.
</p></li>
<li class="listitem"><p>
2 - Zero initialization of the remaining members not copied
over from the parent class.
</p></li>
<li class="listitem"><p>
3 - Invocation of the <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> initializers of all parent
types and the class' type.
</p></li>
<li class="listitem"><p>
4 - Invocation of the class' <a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><code class="function">GClassInitFunc()</code></a> initializer.
</p></li>
</ul></div>
<p>
Since derived classes are partially initialized through a memory copy
of the parent class, the general rule is that <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> and
<a class="link" href="gobject-Type-Information.html#GBaseFinalizeFunc" title="GBaseFinalizeFunc ()"><code class="function">GBaseFinalizeFunc()</code></a> should take care of necessary reinitialization
and release of those class members that were introduced by the type
that specified these <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a>/<a class="link" href="gobject-Type-Information.html#GBaseFinalizeFunc" title="GBaseFinalizeFunc ()"><code class="function">GBaseFinalizeFunc()</code></a>.
<a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><code class="function">GClassInitFunc()</code></a> should only care about initializing static
class members, while dynamic class members (such as allocated strings
or reference counted resources) are better handled by a <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a>
for this type, so proper initialization of the dynamic class members
is performed for class initialization of derived types as well.
An example may help to correspond the intend of the different class
initializers:
</p>
<p>
</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
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10
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13
14
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16
17
18
19
20
21
22
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25
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31
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33
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41</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">typedef</span><span class="normal"> </span><span class="keyword">struct</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> <a href="gobject-The-Base-Object-Type.html#GObjectClass">GObjectClass</a> parent_class</span><span class="symbol">;</span>
<span class="normal"> <a href="./../glib/glib/glib-Basic-Types.html#gint">gint</a> static_integer</span><span class="symbol">;</span>
<span class="normal"> <a href="./../glib/glib/glib-Basic-Types.html#gchar">gchar</a> </span><span class="symbol">*</span><span class="normal">dynamic_string</span><span class="symbol">;</span>
<span class="cbracket">}</span><span class="normal"> TypeAClass</span><span class="symbol">;</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">type_a_base_class_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TypeAClass </span><span class="symbol">*</span><span class="normal">class</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> class</span><span class="symbol">-&gt;</span><span class="normal">dynamic_string </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-String-Utility-Functions.html#g-strdup">g_strdup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"some string"</span><span class="symbol">);</span>
<span class="cbracket">}</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">type_a_base_class_finalize</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TypeAClass </span><span class="symbol">*</span><span class="normal">class</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-Memory-Allocation.html#g-free">g_free</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">class</span><span class="symbol">-&gt;</span><span class="normal">dynamic_string</span><span class="symbol">);</span>
<span class="cbracket">}</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">type_a_class_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TypeAClass </span><span class="symbol">*</span><span class="normal">class</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> class</span><span class="symbol">-&gt;</span><span class="normal">static_integer </span><span class="symbol">=</span><span class="normal"> </span><span class="number">42</span><span class="symbol">;</span>
<span class="cbracket">}</span>
<span class="keyword">typedef</span><span class="normal"> </span><span class="keyword">struct</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> TypeAClass parent_class</span><span class="symbol">;</span>
<span class="normal"> <a href="./../glib/glib/glib-Basic-Types.html#gfloat">gfloat</a> static_float</span><span class="symbol">;</span>
<span class="normal"> <a href="./../glib/glib/glib-Strings.html#GString">GString</a> </span><span class="symbol">*</span><span class="normal">dynamic_gstring</span><span class="symbol">;</span>
<span class="cbracket">}</span><span class="normal"> TypeBClass</span><span class="symbol">;</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">type_b_base_class_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TypeBClass </span><span class="symbol">*</span><span class="normal">class</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> class</span><span class="symbol">-&gt;</span><span class="normal">dynamic_gstring </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-Strings.html#g-string-new">g_string_new</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"some other string"</span><span class="symbol">);</span>
<span class="cbracket">}</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">type_b_base_class_finalize</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TypeBClass </span><span class="symbol">*</span><span class="normal">class</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-Strings.html#g-string-free">g_string_free</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">class</span><span class="symbol">-&gt;</span><span class="normal">dynamic_gstring</span><span class="symbol">);</span>
<span class="cbracket">}</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">type_b_class_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TypeBClass </span><span class="symbol">*</span><span class="normal">class</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> class</span><span class="symbol">-&gt;</span><span class="normal">static_float </span><span class="symbol">=</span><span class="normal"> </span><span class="number">3.14159265358979323846</span><span class="symbol">;</span>
<span class="cbracket">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
Initialization of TypeBClass will first cause initialization of
TypeAClass (derived classes reference their parent classes, see
<a class="link" href="gobject-Type-Information.html#g-type-class-ref" title="g_type_class_ref ()"><code class="function">g_type_class_ref()</code></a> on this).
Initialization of TypeAClass roughly involves zero-initializing its fields,
then calling its <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> <code class="function">type_a_base_class_init()</code> to allocate
its dynamic members (dynamic_string), and finally calling its <a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><code class="function">GClassInitFunc()</code></a>
<code class="function">type_a_class_init()</code> to initialize its static members (static_integer).
The first step in the initialization process of TypeBClass is then
a plain memory copy of the contents of TypeAClass into TypeBClass and
zero-initialization of the remaining fields in TypeBClass.
The dynamic members of TypeAClass within TypeBClass now need
reinitialization which is performed by calling <code class="function">type_a_base_class_init()</code>
with an argument of TypeBClass.
After that, the <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> of TypeBClass, <code class="function">type_b_base_class_init()</code>
is called to allocate the dynamic members of TypeBClass (dynamic_gstring),
and finally the <a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><code class="function">GClassInitFunc()</code></a> of TypeBClass, <code class="function">type_b_class_init()</code>,
is called to complete the initialization process with the static members
(static_float).
Corresponding finalization counter parts to the <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> functions
have to be provided to release allocated resources at class finalization
time.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to initialize.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>class_data</code></em> :</span></p></td>
<td>The <em class="parameter"><code>class_data</code></em> member supplied via the <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GClassFinalizeFunc ()">
<a name="GClassFinalizeFunc"></a><h3>GClassFinalizeFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GClassFinalizeFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> class_data</code></em>);</pre>
<p>
A callback function used by the type system to finalize a class.
This function is rarely needed, as dynamically allocated class resources
should be handled by <a class="link" href="gobject-Type-Information.html#GBaseInitFunc" title="GBaseInitFunc ()"><code class="function">GBaseInitFunc()</code></a> and <a class="link" href="gobject-Type-Information.html#GBaseFinalizeFunc" title="GBaseFinalizeFunc ()"><code class="function">GBaseFinalizeFunc()</code></a>.
Also, specification of a <a class="link" href="gobject-Type-Information.html#GClassFinalizeFunc" title="GClassFinalizeFunc ()"><code class="function">GClassFinalizeFunc()</code></a> in the <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>
structure of a static type is invalid, because classes of static types
will never be finalized (they are artificially kept alive when their
reference count drops to zero).
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to finalize.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>class_data</code></em> :</span></p></td>
<td>The <em class="parameter"><code>class_data</code></em> member supplied via the <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GInstanceInitFunc ()">
<a name="GInstanceInitFunc"></a><h3>GInstanceInitFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GInstanceInitFunc) (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> *instance</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);</pre>
<p>
A callback function used by the type system to initialize a new
instance of a type. This function initializes all instance members and
allocates any resources required by it.
Initialization of a derived instance involves calling all its parent
types instance initializers, so the class member of the instance
is altered during its initialization to always point to the class that
belongs to the type the current initializer was introduced for.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>The instance to initialize.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The class of the type the instance is created for.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GInterfaceInitFunc ()">
<a name="GInterfaceInitFunc"></a><h3>GInterfaceInitFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GInterfaceInitFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> iface_data</code></em>);</pre>
<p>
A callback function used by the type system to initialize a new
interface. This function should initialize all internal data and
allocate any resources required by the interface.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_iface</code></em> :</span></p></td>
<td>The interface structure to initialize.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>iface_data</code></em> :</span></p></td>
<td>The <em class="parameter"><code>interface_data</code></em> supplied via the <a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> structure.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GInterfaceFinalizeFunc ()">
<a name="GInterfaceFinalizeFunc"></a><h3>GInterfaceFinalizeFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GInterfaceFinalizeFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> iface_data</code></em>);</pre>
<p>
A callback function used by the type system to finalize an interface.
This function should destroy any internal data and release any resources
allocated by the corresponding <a class="link" href="gobject-Type-Information.html#GInterfaceInitFunc" title="GInterfaceInitFunc ()"><code class="function">GInterfaceInitFunc()</code></a> function.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_iface</code></em> :</span></p></td>
<td>The interface structure to finalize.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>iface_data</code></em> :</span></p></td>
<td>The <em class="parameter"><code>interface_data</code></em> supplied via the <a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> structure.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="GTypeClassCacheFunc ()">
<a name="GTypeClassCacheFunc"></a><h3>GTypeClassCacheFunc ()</h3>
<pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> (*GTypeClassCacheFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> cache_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> *g_class</code></em>);</pre>
<p>
A callback function which is called when the reference count of a class
drops to zero. It may use <a class="link" href="gobject-Type-Information.html#g-type-class-ref" title="g_type_class_ref ()"><code class="function">g_type_class_ref()</code></a> to prevent the class from
being freed. You should not call <a class="link" href="gobject-Type-Information.html#g-type-class-unref" title="g_type_class_unref ()"><code class="function">g_type_class_unref()</code></a> from a
<a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> function to prevent infinite recursion, use
<a class="link" href="gobject-Type-Information.html#g-type-class-unref-uncached" title="g_type_class_unref_uncached ()"><code class="function">g_type_class_unref_uncached()</code></a> instead.
</p>
<p>
The functions have to check the class id passed in to figure
whether they actually want to cache the class of this type, since all
classes are routed through the same <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> chain.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>cache_data</code></em> :</span></p></td>
<td>data that was given to the <a class="link" href="gobject-Type-Information.html#g-type-add-class-cache-func" title="g_type_add_class_cache_func ()"><code class="function">g_type_add_class_cache_func()</code></a> call
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure which is unreferenced
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> to stop further <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>s from being
called, <a href="./../glib/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> to continue.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="enum GTypeFlags">
<a name="GTypeFlags"></a><h3>enum GTypeFlags</h3>
<pre class="programlisting">typedef enum /*&lt; skip &gt;*/
{
G_TYPE_FLAG_ABSTRACT = (1 &lt;&lt; 4),
G_TYPE_FLAG_VALUE_ABSTRACT = (1 &lt;&lt; 5)
} GTypeFlags;
</pre>
<p>
Bit masks used to check or determine characteristics of a type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><a name="G-TYPE-FLAG-ABSTRACT:CAPS"></a><span class="term"><code class="literal">G_TYPE_FLAG_ABSTRACT</code></span></p></td>
<td>Indicates an abstract type. No instances can be
created for an abstract type.
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-FLAG-VALUE-ABSTRACT:CAPS"></a><span class="term"><code class="literal">G_TYPE_FLAG_VALUE_ABSTRACT</code></span></p></td>
<td>Indicates an abstract value type, i.e. a type
that introduces a value table, but can't be used for
<a class="link" href="gobject-Generic-values.html#g-value-init" title="g_value_init ()"><code class="function">g_value_init()</code></a>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="enum GTypeFundamentalFlags">
<a name="GTypeFundamentalFlags"></a><h3>enum GTypeFundamentalFlags</h3>
<pre class="programlisting">typedef enum /*&lt; skip &gt;*/
{
G_TYPE_FLAG_CLASSED = (1 &lt;&lt; 0),
G_TYPE_FLAG_INSTANTIATABLE = (1 &lt;&lt; 1),
G_TYPE_FLAG_DERIVABLE = (1 &lt;&lt; 2),
G_TYPE_FLAG_DEEP_DERIVABLE = (1 &lt;&lt; 3)
} GTypeFundamentalFlags;
</pre>
<p>
Bit masks used to check or determine specific characteristics of a
fundamental type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><a name="G-TYPE-FLAG-CLASSED:CAPS"></a><span class="term"><code class="literal">G_TYPE_FLAG_CLASSED</code></span></p></td>
<td>Indicates a classed type.
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-FLAG-INSTANTIATABLE:CAPS"></a><span class="term"><code class="literal">G_TYPE_FLAG_INSTANTIATABLE</code></span></p></td>
<td>Indicates an instantiable type (implies classed).
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-FLAG-DERIVABLE:CAPS"></a><span class="term"><code class="literal">G_TYPE_FLAG_DERIVABLE</code></span></p></td>
<td>Indicates a flat derivable type.
</td>
</tr>
<tr>
<td><p><a name="G-TYPE-FLAG-DEEP-DERIVABLE:CAPS"></a><span class="term"><code class="literal">G_TYPE_FLAG_DEEP_DERIVABLE</code></span></p></td>
<td>Indicates a deep derivable type (implies derivable).
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_register_static ()">
<a name="g-type-register-static"></a><h3>g_type_register_static ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_register_static (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> parent_type</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> *info</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);</pre>
<p>
Registers <em class="parameter"><code>type_name</code></em> as the name of a new static type derived from
<em class="parameter"><code>parent_type</code></em>. The type system uses the information contained in the
<a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure pointed to by <em class="parameter"><code>info</code></em> to manage the type and its
instances (if not abstract). The value of <em class="parameter"><code>flags</code></em> determines the nature
(e.g. abstract or not) of the type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>parent_type</code></em> :</span></p></td>
<td>Type from which this type will be derived.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>type_name</code></em> :</span></p></td>
<td>0-terminated string used as the name of the new type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>info</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure for this type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>flags</code></em> :</span></p></td>
<td>Bitwise combination of <a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> values.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The new type identifier.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_register_static_simple ()">
<a name="g-type-register-static-simple"></a><h3>g_type_register_static_simple ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_register_static_simple (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> parent_type</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> class_size</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GClassInitFunc" title="GClassInitFunc ()"><span class="type">GClassInitFunc</span></a> class_init</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a> instance_size</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GInstanceInitFunc" title="GInstanceInitFunc ()"><span class="type">GInstanceInitFunc</span></a> instance_init</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);</pre>
<p>
Registers <em class="parameter"><code>type_name</code></em> as the name of a new static type derived from
<em class="parameter"><code>parent_type</code></em>. The value of <em class="parameter"><code>flags</code></em> determines the nature (e.g.
abstract or not) of the type. It works by filling a <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>
struct and calling <a class="link" href="gobject-Type-Information.html#g-type-register-static" title="g_type_register_static ()"><code class="function">g_type_register_static()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>parent_type</code></em> :</span></p></td>
<td>Type from which this type will be derived.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>type_name</code></em> :</span></p></td>
<td>0-terminated string used as the name of the new type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>class_size</code></em> :</span></p></td>
<td>Size of the class structure (see <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>)
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>class_init</code></em> :</span></p></td>
<td>Location of the class initialization function (see <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>)
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance_size</code></em> :</span></p></td>
<td>Size of the instance structure (see <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>)
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance_init</code></em> :</span></p></td>
<td>Location of the instance initialization function (see <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a>)
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>flags</code></em> :</span></p></td>
<td>Bitwise combination of <a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> values.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The new type identifier.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.12</p>
</div>
<hr>
<div class="refsect2" title="g_type_register_dynamic ()">
<a name="g-type-register-dynamic"></a><h3>g_type_register_dynamic ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_register_dynamic (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> parent_type</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code><a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> *plugin</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);</pre>
<p>
Registers <em class="parameter"><code>type_name</code></em> as the name of a new dynamic type derived from
<em class="parameter"><code>parent_type</code></em>. The type system uses the information contained in the
<a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure pointed to by <em class="parameter"><code>plugin</code></em> to manage the type and its
instances (if not abstract). The value of <em class="parameter"><code>flags</code></em> determines the nature
(e.g. abstract or not) of the type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>parent_type</code></em> :</span></p></td>
<td>Type from which this type will be derived.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>type_name</code></em> :</span></p></td>
<td>0-terminated string used as the name of the new type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>plugin</code></em> :</span></p></td>
<td>The <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure to retrieve the <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> from.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>flags</code></em> :</span></p></td>
<td>Bitwise combination of <a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> values.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The new type identifier or <a class="link" href="gobject-Type-Information.html#G-TYPE-INVALID:CAPS" title="G_TYPE_INVALID"><span class="type">G_TYPE_INVALID</span></a> if registration failed.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_register_fundamental ()">
<a name="g-type-register-fundamental"></a><h3>g_type_register_fundamental ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_register_fundamental (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type_id</code></em>,
<em class="parameter"><code>const <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *type_name</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> *info</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GTypeFundamentalInfo" title="GTypeFundamentalInfo"><span class="type">GTypeFundamentalInfo</span></a> *finfo</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> flags</code></em>);</pre>
<p>
Registers <em class="parameter"><code>type_id</code></em> as the predefined identifier and <em class="parameter"><code>type_name</code></em> as the
name of a fundamental type. The type system uses the information
contained in the <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure pointed to by <em class="parameter"><code>info</code></em> and the
<a class="link" href="gobject-Type-Information.html#GTypeFundamentalInfo" title="GTypeFundamentalInfo"><span class="type">GTypeFundamentalInfo</span></a> structure pointed to by <em class="parameter"><code>finfo</code></em> to manage the
type and its instances. The value of <em class="parameter"><code>flags</code></em> determines additional
characteristics of the fundamental type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type_id</code></em> :</span></p></td>
<td>A predefined type identifier.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>type_name</code></em> :</span></p></td>
<td>0-terminated string used as the name of the new type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>info</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> structure for this type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>finfo</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeFundamentalInfo" title="GTypeFundamentalInfo"><span class="type">GTypeFundamentalInfo</span></a> structure for this type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>flags</code></em> :</span></p></td>
<td>Bitwise combination of <a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> values.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The predefined type identifier.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_add_interface_static ()">
<a name="g-type-add-interface-static"></a><h3>g_type_add_interface_static ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_add_interface_static (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> instance_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code>const <a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> *info</code></em>);</pre>
<p>
Adds the static <em class="parameter"><code>interface_type</code></em> to <em class="parameter"><code>instantiable_type</code></em>. The information
contained in the <span class="type">GTypeInterfaceInfo</span> structure pointed to by <em class="parameter"><code>info</code></em>
is used to manage the relationship.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance_type</code></em> :</span></p></td>
<td>
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an instantiable type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>interface_type</code></em> :</span></p></td>
<td>
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an interface type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>info</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> structure for this
(<em class="parameter"><code>instance_type</code></em>, <em class="parameter"><code>interface_type</code></em>) combination.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_add_interface_dynamic ()">
<a name="g-type-add-interface-dynamic"></a><h3>g_type_add_interface_dynamic ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_add_interface_dynamic (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> instance_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code><a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> *plugin</code></em>);</pre>
<p>
Adds the dynamic <em class="parameter"><code>interface_type</code></em> to <em class="parameter"><code>instantiable_type</code></em>. The information
contained in the <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure pointed to by <em class="parameter"><code>plugin</code></em>
is used to manage the relationship.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance_type</code></em> :</span></p></td>
<td>the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an instantiable type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>interface_type</code></em> :</span></p></td>
<td>the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an interface type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>plugin</code></em> :</span></p></td>
<td>the <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure to retrieve the <a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> from.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_interface_add_prerequisite ()">
<a name="g-type-interface-add-prerequisite"></a><h3>g_type_interface_add_prerequisite ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_interface_add_prerequisite (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> prerequisite_type</code></em>);</pre>
<p>
Adds <em class="parameter"><code>prerequisite_type</code></em> to the list of prerequisites of <em class="parameter"><code>interface_type</code></em>.
This means that any type implementing <em class="parameter"><code>interface_type</code></em> must also implement
<em class="parameter"><code>prerequisite_type</code></em>. Prerequisites can be thought of as an alternative to
interface derivation (which GType doesn't support). An interface can have
at most one instantiatable prerequisite type.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>interface_type</code></em> :</span></p></td>
<td>
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an interface type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>prerequisite_type</code></em> :</span></p></td>
<td>
<a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an interface or instantiatable type.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_get_plugin ()">
<a name="g-type-get-plugin"></a><h3>g_type_get_plugin ()</h3>
<pre class="programlisting"><a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="returnvalue">GTypePlugin</span></a>* g_type_get_plugin (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Returns the <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure for <em class="parameter"><code>type</code></em> or
<a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if <em class="parameter"><code>type</code></em> does not have a <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> to retrieve the plugin for.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The corresponding plugin if <em class="parameter"><code>type</code></em> is a dynamic type,
<a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> otherwise.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_interface_get_plugin ()">
<a name="g-type-interface-get-plugin"></a><h3>g_type_interface_get_plugin ()</h3>
<pre class="programlisting"><a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="returnvalue">GTypePlugin</span></a>* g_type_interface_get_plugin (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> instance_type</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> interface_type</code></em>);</pre>
<p>
Returns the <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure for the dynamic interface
<em class="parameter"><code>interface_type</code></em> which has been added to <em class="parameter"><code>instance_type</code></em>, or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if
<em class="parameter"><code>interface_type</code></em> has not been added to <em class="parameter"><code>instance_type</code></em> or does not
have a <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> structure. See <a class="link" href="gobject-Type-Information.html#g-type-add-interface-dynamic" title="g_type_add_interface_dynamic ()"><code class="function">g_type_add_interface_dynamic()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>instance_type</code></em> :</span></p></td>
<td>the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an instantiatable type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>interface_type</code></em> :</span></p></td>
<td>the <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value of an interface type.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> the <a class="link" href="GTypePlugin.html" title="GTypePlugin"><span class="type">GTypePlugin</span></a> for the dynamic interface <em class="parameter"><code>interface_type</code></em>
of <em class="parameter"><code>instance_type</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_fundamental_next ()">
<a name="g-type-fundamental-next"></a><h3>g_type_fundamental_next ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_fundamental_next (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>
Returns the next free fundamental type id which can be used to
register a new fundamental type with <a class="link" href="gobject-Type-Information.html#g-type-register-fundamental" title="g_type_register_fundamental ()"><code class="function">g_type_register_fundamental()</code></a>.
The returned type ID represents the highest currently registered
fundamental type identifier.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> The nextmost fundamental type ID to be registered,
or 0 if the type system ran out of fundamental type IDs.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_fundamental ()">
<a name="g-type-fundamental"></a><h3>g_type_fundamental ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="returnvalue">GType</span></a> g_type_fundamental (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type_id</code></em>);</pre>
<p>
Internal function, used to extract the fundamental type ID portion.
use <a class="link" href="gobject-Type-Information.html#G-TYPE-FUNDAMENTAL:CAPS" title="G_TYPE_FUNDAMENTAL()"><code class="function">G_TYPE_FUNDAMENTAL()</code></a> instead.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type_id</code></em> :</span></p></td>
<td>valid type ID
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> fundamental type ID
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_create_instance ()">
<a name="g-type-create-instance"></a><h3>g_type_create_instance ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="returnvalue">GTypeInstance</span></a>* g_type_create_instance (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Creates and initializes an instance of <em class="parameter"><code>type</code></em> if <em class="parameter"><code>type</code></em> is valid and
can be instantiated. The type system only performs basic allocation
and structure setups for instances: actual instance creation should
happen through functions supplied by the type's fundamental type
implementation. So use of <a class="link" href="gobject-Type-Information.html#g-type-create-instance" title="g_type_create_instance ()"><code class="function">g_type_create_instance()</code></a> is reserved for
implementators of fundamental types only. E.g. instances of the
<a class="link" href="gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a> hierarchy should be created via <a class="link" href="gobject-The-Base-Object-Type.html#g-object-new" title="g_object_new ()"><code class="function">g_object_new()</code></a> and
<span class="emphasis"><em>never</em></span> directly through
<a class="link" href="gobject-Type-Information.html#g-type-create-instance" title="g_type_create_instance ()"><code class="function">g_type_create_instance()</code></a> which doesn't handle things like singleton
objects or object construction. Note: Do <span class="emphasis"><em>not</em></span>
use this function, unless you're implementing a fundamental
type. Also language bindings should <span class="emphasis"><em>not</em></span> use
this function but <a class="link" href="gobject-The-Base-Object-Type.html#g-object-new" title="g_object_new ()"><code class="function">g_object_new()</code></a> instead.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>An instantiatable type to create an instance for.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> An allocated and initialized instance, subject to further
treatment by the fundamental type implementation.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_free_instance ()">
<a name="g-type-free-instance"></a><h3>g_type_free_instance ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_free_instance (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInstance" title="GTypeInstance"><span class="type">GTypeInstance</span></a> *instance</code></em>);</pre>
<p>
Frees an instance of a type, returning it to the instance pool for
the type, if there is one.
</p>
<p>
Like <a class="link" href="gobject-Type-Information.html#g-type-create-instance" title="g_type_create_instance ()"><code class="function">g_type_create_instance()</code></a>, this function is reserved for
implementors of fundamental types.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>instance</code></em> :</span></p></td>
<td>an instance of a type.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_add_class_cache_func ()">
<a name="g-type-add-class-cache-func"></a><h3>g_type_add_class_cache_func ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_add_class_cache_func (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> cache_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> cache_func</code></em>);</pre>
<p>
Adds a <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> to be called before the reference count of a
class goes from one to zero. This can be used to prevent premature class
destruction. All installed <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> functions will be chained
until one of them returns <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>. The functions have to check the class id
passed in to figure whether they actually want to cache the class of this
type, since all classes are routed through the same <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>
chain.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>cache_data</code></em> :</span></p></td>
<td>data to be passed to <em class="parameter"><code>cache_func</code></em>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>cache_func</code></em> :</span></p></td>
<td>a <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_remove_class_cache_func ()">
<a name="g-type-remove-class-cache-func"></a><h3>g_type_remove_class_cache_func ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_remove_class_cache_func (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> cache_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a> cache_func</code></em>);</pre>
<p>
Removes a previously installed <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>. The cache
maintained by <em class="parameter"><code>cache_func</code></em> has to be empty when calling
<a class="link" href="gobject-Type-Information.html#g-type-remove-class-cache-func" title="g_type_remove_class_cache_func ()"><code class="function">g_type_remove_class_cache_func()</code></a> to avoid leaks.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>cache_data</code></em> :</span></p></td>
<td>data that was given when adding <em class="parameter"><code>cache_func</code></em>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>cache_func</code></em> :</span></p></td>
<td>a <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_class_unref_uncached ()">
<a name="g-type-class-unref-uncached"></a><h3>g_type_class_unref_uncached ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_class_unref_uncached (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_class</code></em>);</pre>
<p>
A variant of <a class="link" href="gobject-Type-Information.html#g-type-class-unref" title="g_type_class_unref ()"><code class="function">g_type_class_unref()</code></a> for use in <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>
implementations. It unreferences a class without consulting the chain
of <a class="link" href="gobject-Type-Information.html#GTypeClassCacheFunc" title="GTypeClassCacheFunc ()"><span class="type">GTypeClassCacheFunc</span></a>s, avoiding the recursion which would occur
otherwise.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>g_class</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GTypeClass" title="GTypeClass"><span class="type">GTypeClass</span></a> structure to unreference.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="g_type_add_interface_check ()">
<a name="g-type-add-interface-check"></a><h3>g_type_add_interface_check ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_add_interface_check (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> check_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInterfaceCheckFunc" title="GTypeInterfaceCheckFunc ()"><span class="type">GTypeInterfaceCheckFunc</span></a> check_func</code></em>);</pre>
<p>
Adds a function to be called after an interface vtable is
initialized for any class (i.e. after the <em class="parameter"><code>interface_init</code></em> member of
<a class="link" href="gobject-Type-Information.html#GInterfaceInfo" title="GInterfaceInfo"><span class="type">GInterfaceInfo</span></a> has been called).
</p>
<p>
This function is useful when you want to check an invariant that
depends on the interfaces of a class. For instance, the
implementation of <a class="link" href="gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a> uses this facility to check that an
object implements all of the properties that are defined on its
interfaces.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>check_data</code></em> :</span></p></td>
<td>data to pass to <em class="parameter"><code>check_func</code></em>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>check_func</code></em> :</span></p></td>
<td>function to be called after each interface
is initialized.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_remove_interface_check ()">
<a name="g-type-remove-interface-check"></a><h3>g_type_remove_interface_check ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> g_type_remove_interface_check (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> check_data</code></em>,
<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GTypeInterfaceCheckFunc" title="GTypeInterfaceCheckFunc ()"><span class="type">GTypeInterfaceCheckFunc</span></a> check_func</code></em>);</pre>
<p>
Removes an interface check function added with
<a class="link" href="gobject-Type-Information.html#g-type-add-interface-check" title="g_type_add_interface_check ()"><code class="function">g_type_add_interface_check()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>check_data</code></em> :</span></p></td>
<td>callback data passed to <a class="link" href="gobject-Type-Information.html#g-type-add-interface-check" title="g_type_add_interface_check ()"><code class="function">g_type_add_interface_check()</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>check_func</code></em> :</span></p></td>
<td>callback function passed to <a class="link" href="gobject-Type-Information.html#g-type-add-interface-check" title="g_type_add_interface_check ()"><code class="function">g_type_add_interface_check()</code></a>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="GTypeInterfaceCheckFunc ()">
<a name="GTypeInterfaceCheckFunc"></a><h3>GTypeInterfaceCheckFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GTypeInterfaceCheckFunc) (<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> check_data</code></em>,
<em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> g_iface</code></em>);</pre>
<p>
A callback called after an interface vtable is initialized.
See <a class="link" href="gobject-Type-Information.html#g-type-add-interface-check" title="g_type_add_interface_check ()"><code class="function">g_type_add_interface_check()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>check_data</code></em> :</span></p></td>
<td>data passed to <a class="link" href="gobject-Type-Information.html#g-type-add-interface-check" title="g_type_add_interface_check ()"><code class="function">g_type_add_interface_check()</code></a>.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>g_iface</code></em> :</span></p></td>
<td>the interface that has been initialized
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="g_type_value_table_peek ()">
<a name="g-type-value-table-peek"></a><h3>g_type_value_table_peek ()</h3>
<pre class="programlisting"><a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="returnvalue">GTypeValueTable</span></a>* g_type_value_table_peek (<em class="parameter"><code><a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> type</code></em>);</pre>
<p>
Returns the location of the <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a> associated with <em class="parameter"><code>type</code></em>.
<span class="emphasis"><em>Note that this function should only be used from source code
that implements or has internal knowledge of the implementation of
<em class="parameter"><code>type</code></em>.</em></span>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>A <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> value.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td> Location of the <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a> associated with <em class="parameter"><code>type</code></em> or
<a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if there is no <a class="link" href="gobject-Type-Information.html#GTypeValueTable" title="GTypeValueTable"><span class="type">GTypeValueTable</span></a> associated with <em class="parameter"><code>type</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_TYPE()">
<a name="G-DEFINE-TYPE:CAPS"></a><h3>G_DEFINE_TYPE()</h3>
<pre class="programlisting">#define G_DEFINE_TYPE(TN, t_n, T_P) G_DEFINE_TYPE_EXTENDED (TN, t_n, T_P, 0, {})
</pre>
<p>
A convenience macro for type implementations, which declares a
class initialization function, an instance initialization function (see <a class="link" href="gobject-Type-Information.html#GTypeInfo" title="GTypeInfo"><span class="type">GTypeInfo</span></a> for information about
these) and a static variable named <em class="parameter"><code>t_n</code></em>_parent_class pointing to the parent class. Furthermore, it defines
a *_get_type() function. See <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()"><code class="function">G_DEFINE_TYPE_EXTENDED()</code></a> for an example.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type, in lowercase, with words
separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the parent type.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_TYPE_WITH_CODE()">
<a name="G-DEFINE-TYPE-WITH-CODE:CAPS"></a><h3>G_DEFINE_TYPE_WITH_CODE()</h3>
<pre class="programlisting">#define G_DEFINE_TYPE_WITH_CODE(TN, t_n, T_P, _C_) _G_DEFINE_TYPE_EXTENDED_BEGIN (TN, t_n, T_P, 0) {_C_;} _G_DEFINE_TYPE_EXTENDED_END()
</pre>
<p>
A convenience macro for type implementations.
Similar to <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE:CAPS" title="G_DEFINE_TYPE()"><code class="function">G_DEFINE_TYPE()</code></a>, but allows you to insert custom code into the
*_get_type() function, e.g. interface implementations via <a class="link" href="gobject-Type-Information.html#G-IMPLEMENT-INTERFACE:CAPS" title="G_IMPLEMENT_INTERFACE()"><code class="function">G_IMPLEMENT_INTERFACE()</code></a>.
See <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()"><code class="function">G_DEFINE_TYPE_EXTENDED()</code></a> for an example.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type in lowercase, with words separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the parent type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>_C_</code></em> :</span></p></td>
<td>Custom code that gets inserted in the *_get_type() function.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_ABSTRACT_TYPE()">
<a name="G-DEFINE-ABSTRACT-TYPE:CAPS"></a><h3>G_DEFINE_ABSTRACT_TYPE()</h3>
<pre class="programlisting">#define G_DEFINE_ABSTRACT_TYPE(TN, t_n, T_P) G_DEFINE_TYPE_EXTENDED (TN, t_n, T_P, G_TYPE_FLAG_ABSTRACT, {})
</pre>
<p>
A convenience macro for type implementations.
Similar to <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE:CAPS" title="G_DEFINE_TYPE()"><code class="function">G_DEFINE_TYPE()</code></a>, but defines an abstract type.
See <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()"><code class="function">G_DEFINE_TYPE_EXTENDED()</code></a> for an example.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type, in lowercase, with words
separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the parent type.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_ABSTRACT_TYPE_WITH_CODE()">
<a name="G-DEFINE-ABSTRACT-TYPE-WITH-CODE:CAPS"></a><h3>G_DEFINE_ABSTRACT_TYPE_WITH_CODE()</h3>
<pre class="programlisting">#define G_DEFINE_ABSTRACT_TYPE_WITH_CODE(TN, t_n, T_P, _C_) _G_DEFINE_TYPE_EXTENDED_BEGIN (TN, t_n, T_P, G_TYPE_FLAG_ABSTRACT) {_C_;} _G_DEFINE_TYPE_EXTENDED_END()
</pre>
<p>
A convenience macro for type implementations.
Similar to <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-WITH-CODE:CAPS" title="G_DEFINE_TYPE_WITH_CODE()"><code class="function">G_DEFINE_TYPE_WITH_CODE()</code></a>, but defines an abstract type and allows you to
insert custom code into the *_get_type() function, e.g. interface implementations
via <a class="link" href="gobject-Type-Information.html#G-IMPLEMENT-INTERFACE:CAPS" title="G_IMPLEMENT_INTERFACE()"><code class="function">G_IMPLEMENT_INTERFACE()</code></a>. See <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()"><code class="function">G_DEFINE_TYPE_EXTENDED()</code></a> for an example.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type, in lowercase, with words
separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the parent type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>_C_</code></em> :</span></p></td>
<td>Custom code that gets inserted in the @<code class="function">type_name_get_type()</code> function.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_INTERFACE()">
<a name="G-DEFINE-INTERFACE:CAPS"></a><h3>G_DEFINE_INTERFACE()</h3>
<pre class="programlisting">#define G_DEFINE_INTERFACE(TN, t_n, T_P) G_DEFINE_INTERFACE_WITH_CODE(TN, t_n, T_P, ;)
</pre>
<p>
A convenience macro for <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> definitions, which declares
a default vtable initialization function and defines a *_get_type()
function.
</p>
<p>
The macro expects the interface initialization function to have the
name <code class="literal">t_n ## _default_init</code>, and the interface
structure to have the name <code class="literal">TN ## Interface</code>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type, in lowercase, with words separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the prerequisite type for the interface, or 0
(<a class="link" href="gobject-Type-Information.html#G-TYPE-INVALID:CAPS" title="G_TYPE_INVALID"><code class="literal">G_TYPE_INVALID</code></a>) for no prerequisite type.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.24</p>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_INTERFACE_WITH_CODE()">
<a name="G-DEFINE-INTERFACE-WITH-CODE:CAPS"></a><h3>G_DEFINE_INTERFACE_WITH_CODE()</h3>
<pre class="programlisting">#define G_DEFINE_INTERFACE_WITH_CODE(TN, t_n, T_P, _C_) _G_DEFINE_INTERFACE_EXTENDED_BEGIN(TN, t_n, T_P) {_C_;} _G_DEFINE_INTERFACE_EXTENDED_END()
</pre>
<p>
A convenience macro for <a class="link" href="gobject-Type-Information.html#GTypeInterface" title="GTypeInterface"><span class="type">GTypeInterface</span></a> definitions. Similar to
<a class="link" href="gobject-Type-Information.html#G-DEFINE-INTERFACE:CAPS" title="G_DEFINE_INTERFACE()"><code class="function">G_DEFINE_INTERFACE()</code></a>, but allows you to insert custom code into the
*_get_type() function, e.g. additional interface implementations
via <a class="link" href="gobject-Type-Information.html#G-IMPLEMENT-INTERFACE:CAPS" title="G_IMPLEMENT_INTERFACE()"><code class="function">G_IMPLEMENT_INTERFACE()</code></a>, or additional prerequisite types. See
<a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()"><code class="function">G_DEFINE_TYPE_EXTENDED()</code></a> for a similar example using
<a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-WITH-CODE:CAPS" title="G_DEFINE_TYPE_WITH_CODE()"><code class="function">G_DEFINE_TYPE_WITH_CODE()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type, in lowercase, with words separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the prerequisite type for the interface, or 0
(<a class="link" href="gobject-Type-Information.html#G-TYPE-INVALID:CAPS" title="G_TYPE_INVALID"><code class="literal">G_TYPE_INVALID</code></a>) for no prerequisite type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>_C_</code></em> :</span></p></td>
<td>Custom code that gets inserted in the *_get_type() function.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.24</p>
</div>
<hr>
<div class="refsect2" title="G_IMPLEMENT_INTERFACE()">
<a name="G-IMPLEMENT-INTERFACE:CAPS"></a><h3>G_IMPLEMENT_INTERFACE()</h3>
<pre class="programlisting">#define G_IMPLEMENT_INTERFACE(TYPE_IFACE, iface_init)</pre>
<p>
A convenience macro to ease interface addition in the <em class="parameter"><code>_C_</code></em> section
of <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-WITH-CODE:CAPS" title="G_DEFINE_TYPE_WITH_CODE()"><code class="function">G_DEFINE_TYPE_WITH_CODE()</code></a> or <a class="link" href="gobject-Type-Information.html#G-DEFINE-ABSTRACT-TYPE-WITH-CODE:CAPS" title="G_DEFINE_ABSTRACT_TYPE_WITH_CODE()"><code class="function">G_DEFINE_ABSTRACT_TYPE_WITH_CODE()</code></a>.
See <a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS" title="G_DEFINE_TYPE_EXTENDED()"><code class="function">G_DEFINE_TYPE_EXTENDED()</code></a> for an example.
</p>
<p>
Note that this macro can only be used together with the G_DEFINE_TYPE_*
macros, since it depends on variable names from those macros.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TYPE_IFACE</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the interface to add
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>iface_init</code></em> :</span></p></td>
<td>The interface init function
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_DEFINE_TYPE_EXTENDED()">
<a name="G-DEFINE-TYPE-EXTENDED:CAPS"></a><h3>G_DEFINE_TYPE_EXTENDED()</h3>
<pre class="programlisting">#define G_DEFINE_TYPE_EXTENDED(TN, t_n, T_P, _f_, _C_) _G_DEFINE_TYPE_EXTENDED_BEGIN (TN, t_n, T_P, _f_) {_C_;} _G_DEFINE_TYPE_EXTENDED_END()
</pre>
<p>
The most general convenience macro for type implementations, on which
<a class="link" href="gobject-Type-Information.html#G-DEFINE-TYPE:CAPS" title="G_DEFINE_TYPE()"><code class="function">G_DEFINE_TYPE()</code></a>, etc are based.
</p>
<p>
</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="function"><a href="gobject-Type-Information.html#G-DEFINE-TYPE-EXTENDED:CAPS">G_DEFINE_TYPE_EXTENDED</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GtkGadget</span><span class="symbol">,</span>
<span class="normal"> gtk_gadget</span><span class="symbol">,</span>
<span class="normal"> GTK_TYPE_WIDGET</span><span class="symbol">,</span>
<span class="normal"> </span><span class="number">0</span><span class="symbol">,</span>
<span class="normal"> </span><span class="function"><a href="gobject-Type-Information.html#G-IMPLEMENT-INTERFACE:CAPS">G_IMPLEMENT_INTERFACE</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">TYPE_GIZMO</span><span class="symbol">,</span>
<span class="normal"> gtk_gadget_gizmo_init</span><span class="symbol">));</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
expands to
</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">static</span><span class="normal"> </span><span class="type">void</span><span class="normal"> </span><span class="function">gtk_gadget_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GtkGadget </span><span class="symbol">*</span><span class="normal">self</span><span class="symbol">);</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span><span class="normal"> </span><span class="function">gtk_gadget_class_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GtkGadgetClass </span><span class="symbol">*</span><span class="normal">klass</span><span class="symbol">);</span>
<span class="keyword">static</span><span class="normal"> <a href="./../glib/glib/glib-Basic-Types.html#gpointer">gpointer</a> gtk_gadget_parent_class </span><span class="symbol">=</span><span class="normal"> <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">;</span>
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span><span class="normal"> </span><span class="function">gtk_gadget_class_intern_init</span><span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="./../glib/glib/glib-Basic-Types.html#gpointer">gpointer</a> klass</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> gtk_gadget_parent_class </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="gobject-Type-Information.html#g-type-class-peek-parent">g_type_class_peek_parent</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">klass</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function">gtk_gadget_class_init</span><span class="normal"> </span><span class="symbol">((</span><span class="normal">GtkGadgetClass</span><span class="symbol">*)</span><span class="normal"> klass</span><span class="symbol">);</span>
<span class="cbracket">}</span>
<span class="normal"><a href="gobject-Type-Information.html#GType">GType</a></span>
<span class="function">gtk_gadget_get_type</span><span class="normal"> </span><span class="symbol">(</span><span class="type">void</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="keyword">static</span><span class="normal"> </span><span class="keyword">volatile</span><span class="normal"> <a href="./../glib/glib/glib-Basic-Types.html#gsize">gsize</a> g_define_type_id__volatile </span><span class="symbol">=</span><span class="normal"> </span><span class="number">0</span><span class="symbol">;</span>
<span class="normal"> </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="function"><a href="./../glib/glib/glib-Threads.html#g-once-init-enter">g_once_init_enter</a></span><span class="normal"> </span><span class="symbol">(&amp;</span><span class="normal">g_define_type_id__volatile</span><span class="symbol">))</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> <a href="gobject-Type-Information.html#GType">GType</a> g_define_type_id </span><span class="symbol">=</span>
<span class="normal"> </span><span class="function"><a href="gobject-Type-Information.html#g-type-register-static-simple">g_type_register_static_simple</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GTK_TYPE_WIDGET</span><span class="symbol">,</span>
<span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-Quarks.html#g-intern-static-string">g_intern_static_string</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"GtkGadget"</span><span class="symbol">),</span>
<span class="normal"> </span><span class="keyword">sizeof</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GtkGadgetClass</span><span class="symbol">),</span>
<span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="gobject-Type-Information.html#GClassInitFunc">GClassInitFunc</a></span><span class="symbol">)</span><span class="normal"> gtk_gadget_class_intern_init</span><span class="symbol">,</span>
<span class="normal"> </span><span class="keyword">sizeof</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GtkGadget</span><span class="symbol">),</span>
<span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="gobject-Type-Information.html#GInstanceInitFunc">GInstanceInitFunc</a></span><span class="symbol">)</span><span class="normal"> gtk_gadget_init</span><span class="symbol">,</span>
<span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="gobject-Type-Information.html#GTypeFlags">GTypeFlags</a></span><span class="symbol">)</span><span class="normal"> flags</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="keyword">static</span><span class="normal"> </span><span class="keyword">const</span><span class="normal"> <a href="gobject-Type-Information.html#GInterfaceInfo">GInterfaceInfo</a> g_implement_interface_info </span><span class="symbol">=</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="gobject-Type-Information.html#GInterfaceInitFunc">GInterfaceInitFunc</a></span><span class="symbol">)</span><span class="normal"> gtk_gadget_gizmo_init</span>
<span class="normal"> </span><span class="cbracket">}</span><span class="symbol">;</span>
<span class="normal"> </span><span class="function"><a href="gobject-Type-Information.html#g-type-add-interface-static">g_type_add_interface_static</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">g_define_type_id</span><span class="symbol">,</span><span class="normal"> TYPE_GIZMO</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">g_implement_interface_info</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="function"><a href="./../glib/glib/glib-Threads.html#g-once-init-leave">g_once_init_leave</a></span><span class="normal"> </span><span class="symbol">(&amp;</span><span class="normal">g_define_type_id__volatile</span><span class="symbol">,</span><span class="normal"> g_define_type_id</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="keyword">return</span><span class="normal"> g_define_type_id__volatile</span><span class="symbol">;</span>
<span class="cbracket">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
The only pieces which have to be manually provided are the definitions of
the instance and class structure and the definitions of the instance and
class init functions.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>TN</code></em> :</span></p></td>
<td>The name of the new type, in Camel case.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>t_n</code></em> :</span></p></td>
<td>The name of the new type, in lowercase, with words
separated by '_'.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>T_P</code></em> :</span></p></td>
<td>The <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> of the parent type.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>_f_</code></em> :</span></p></td>
<td>
<a class="link" href="gobject-Type-Information.html#GTypeFlags" title="enum GTypeFlags"><span class="type">GTypeFlags</span></a> to pass to <a class="link" href="gobject-Type-Information.html#g-type-register-static" title="g_type_register_static ()"><code class="function">g_type_register_static()</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>_C_</code></em> :</span></p></td>
<td>Custom code that gets inserted in the *_get_type() function.
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 2.4</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INVALID">
<a name="G-TYPE-INVALID:CAPS"></a><h3>G_TYPE_INVALID</h3>
<pre class="programlisting">#define G_TYPE_INVALID G_TYPE_MAKE_FUNDAMENTAL (0)
</pre>
<p>
An invalid <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a> used as error return value in some functions which return
a <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_NONE">
<a name="G-TYPE-NONE:CAPS"></a><h3>G_TYPE_NONE</h3>
<pre class="programlisting">#define G_TYPE_NONE G_TYPE_MAKE_FUNDAMENTAL (1)
</pre>
<p>
A fundamental type which is used as a replacement for the C
<code class="literal">void</code> return type.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INTERFACE">
<a name="G-TYPE-INTERFACE:CAPS"></a><h3>G_TYPE_INTERFACE</h3>
<pre class="programlisting">#define G_TYPE_INTERFACE G_TYPE_MAKE_FUNDAMENTAL (2)
</pre>
<p>
The fundamental type from which all interfaces are derived.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_CHAR">
<a name="G-TYPE-CHAR:CAPS"></a><h3>G_TYPE_CHAR</h3>
<pre class="programlisting">#define G_TYPE_CHAR G_TYPE_MAKE_FUNDAMENTAL (3)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a>.
The type designated by G_TYPE_CHAR is unconditionally an 8-bit signed integer.
This may or may not be the same type a the C type "gchar".
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_UCHAR">
<a name="G-TYPE-UCHAR:CAPS"></a><h3>G_TYPE_UCHAR</h3>
<pre class="programlisting">#define G_TYPE_UCHAR G_TYPE_MAKE_FUNDAMENTAL (4)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#guchar"><span class="type">guchar</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_BOOLEAN">
<a name="G-TYPE-BOOLEAN:CAPS"></a><h3>G_TYPE_BOOLEAN</h3>
<pre class="programlisting">#define G_TYPE_BOOLEAN G_TYPE_MAKE_FUNDAMENTAL (5)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INT">
<a name="G-TYPE-INT:CAPS"></a><h3>G_TYPE_INT</h3>
<pre class="programlisting">#define G_TYPE_INT G_TYPE_MAKE_FUNDAMENTAL (6)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gint"><span class="type">gint</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_UINT">
<a name="G-TYPE-UINT:CAPS"></a><h3>G_TYPE_UINT</h3>
<pre class="programlisting">#define G_TYPE_UINT G_TYPE_MAKE_FUNDAMENTAL (7)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_LONG">
<a name="G-TYPE-LONG:CAPS"></a><h3>G_TYPE_LONG</h3>
<pre class="programlisting">#define G_TYPE_LONG G_TYPE_MAKE_FUNDAMENTAL (8)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#glong"><span class="type">glong</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_ULONG">
<a name="G-TYPE-ULONG:CAPS"></a><h3>G_TYPE_ULONG</h3>
<pre class="programlisting">#define G_TYPE_ULONG G_TYPE_MAKE_FUNDAMENTAL (9)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gulong"><span class="type">gulong</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_INT64">
<a name="G-TYPE-INT64:CAPS"></a><h3>G_TYPE_INT64</h3>
<pre class="programlisting">#define G_TYPE_INT64 G_TYPE_MAKE_FUNDAMENTAL (10)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gint64"><span class="type">gint64</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_UINT64">
<a name="G-TYPE-UINT64:CAPS"></a><h3>G_TYPE_UINT64</h3>
<pre class="programlisting">#define G_TYPE_UINT64 G_TYPE_MAKE_FUNDAMENTAL (11)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#guint64"><span class="type">guint64</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_ENUM">
<a name="G-TYPE-ENUM:CAPS"></a><h3>G_TYPE_ENUM</h3>
<pre class="programlisting">#define G_TYPE_ENUM G_TYPE_MAKE_FUNDAMENTAL (12)
</pre>
<p>
The fundamental type from which all enumeration types are derived.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FLAGS">
<a name="G-TYPE-FLAGS:CAPS"></a><h3>G_TYPE_FLAGS</h3>
<pre class="programlisting">#define G_TYPE_FLAGS G_TYPE_MAKE_FUNDAMENTAL (13)
</pre>
<p>
The fundamental type from which all flags types are derived.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_FLOAT">
<a name="G-TYPE-FLOAT:CAPS"></a><h3>G_TYPE_FLOAT</h3>
<pre class="programlisting">#define G_TYPE_FLOAT G_TYPE_MAKE_FUNDAMENTAL (14)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_DOUBLE">
<a name="G-TYPE-DOUBLE:CAPS"></a><h3>G_TYPE_DOUBLE</h3>
<pre class="programlisting">#define G_TYPE_DOUBLE G_TYPE_MAKE_FUNDAMENTAL (15)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_STRING">
<a name="G-TYPE-STRING:CAPS"></a><h3>G_TYPE_STRING</h3>
<pre class="programlisting">#define G_TYPE_STRING G_TYPE_MAKE_FUNDAMENTAL (16)
</pre>
<p>
The fundamental type corresponding to nul-terminated C strings.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_POINTER">
<a name="G-TYPE-POINTER:CAPS"></a><h3>G_TYPE_POINTER</h3>
<pre class="programlisting">#define G_TYPE_POINTER G_TYPE_MAKE_FUNDAMENTAL (17)
</pre>
<p>
The fundamental type corresponding to <a href="./../glib/glib/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_BOXED">
<a name="G-TYPE-BOXED:CAPS"></a><h3>G_TYPE_BOXED</h3>
<pre class="programlisting">#define G_TYPE_BOXED G_TYPE_MAKE_FUNDAMENTAL (18)
</pre>
<p>
The fundamental type from which all boxed types are derived.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_PARAM">
<a name="G-TYPE-PARAM:CAPS"></a><h3>G_TYPE_PARAM</h3>
<pre class="programlisting">#define G_TYPE_PARAM G_TYPE_MAKE_FUNDAMENTAL (19)
</pre>
<p>
The fundamental type from which all <a class="link" href="gobject-GParamSpec.html#GParamSpec" title="GParamSpec"><span class="type">GParamSpec</span></a> types are derived.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_OBJECT">
<a name="G-TYPE-OBJECT:CAPS"></a><h3>G_TYPE_OBJECT</h3>
<pre class="programlisting">#define G_TYPE_OBJECT G_TYPE_MAKE_FUNDAMENTAL (20)
</pre>
<p>
The fundamental type for <a class="link" href="gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_GTYPE">
<a name="G-TYPE-GTYPE:CAPS"></a><h3>G_TYPE_GTYPE</h3>
<pre class="programlisting">#define G_TYPE_GTYPE (g_gtype_get_type())
</pre>
<p>
The type for <a class="link" href="gobject-Type-Information.html#GType" title="GType"><span class="type">GType</span></a>.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_RESERVED_GLIB_FIRST">
<a name="G-TYPE-RESERVED-GLIB-FIRST:CAPS"></a><h3>G_TYPE_RESERVED_GLIB_FIRST</h3>
<pre class="programlisting">#define G_TYPE_RESERVED_GLIB_FIRST (21)
</pre>
<p>
First fundamental type number to create a new fundamental type id with
<a class="link" href="gobject-Type-Information.html#G-TYPE-MAKE-FUNDAMENTAL:CAPS" title="G_TYPE_MAKE_FUNDAMENTAL()"><code class="function">G_TYPE_MAKE_FUNDAMENTAL()</code></a> reserved for GLib.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_RESERVED_GLIB_LAST">
<a name="G-TYPE-RESERVED-GLIB-LAST:CAPS"></a><h3>G_TYPE_RESERVED_GLIB_LAST</h3>
<pre class="programlisting">#define G_TYPE_RESERVED_GLIB_LAST (31)
</pre>
<p>
Last fundamental type number reserved for GLib.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_RESERVED_BSE_FIRST">
<a name="G-TYPE-RESERVED-BSE-FIRST:CAPS"></a><h3>G_TYPE_RESERVED_BSE_FIRST</h3>
<pre class="programlisting">#define G_TYPE_RESERVED_BSE_FIRST (32)
</pre>
<p>
First fundamental type number to create a new fundamental type id with
<a class="link" href="gobject-Type-Information.html#G-TYPE-MAKE-FUNDAMENTAL:CAPS" title="G_TYPE_MAKE_FUNDAMENTAL()"><code class="function">G_TYPE_MAKE_FUNDAMENTAL()</code></a> reserved for BSE.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_RESERVED_BSE_LAST">
<a name="G-TYPE-RESERVED-BSE-LAST:CAPS"></a><h3>G_TYPE_RESERVED_BSE_LAST</h3>
<pre class="programlisting">#define G_TYPE_RESERVED_BSE_LAST (48)
</pre>
<p>
Last fundamental type number reserved for BSE.
</p>
</div>
<hr>
<div class="refsect2" title="G_TYPE_RESERVED_USER_FIRST">
<a name="G-TYPE-RESERVED-USER-FIRST:CAPS"></a><h3>G_TYPE_RESERVED_USER_FIRST</h3>
<pre class="programlisting">#define G_TYPE_RESERVED_USER_FIRST (49)
</pre>
<p>
First available fundamental type number to create new fundamental
type id with <a class="link" href="gobject-Type-Information.html#G-TYPE-MAKE-FUNDAMENTAL:CAPS" title="G_TYPE_MAKE_FUNDAMENTAL()"><code class="function">G_TYPE_MAKE_FUNDAMENTAL()</code></a>.
</p>
</div>
</div>
</div>
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