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| <div class="sect1" title="Object Destruction"> |
| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="howto-gobject-destruction"></a>Object Destruction</h2></div></div></div> |
| <p> |
| Again, it is often difficult to figure out which mechanism to use to |
| hook into the object's destruction process: when the last |
| <code class="function"><a class="link" href="gobject-The-Base-Object-Type.html#g-object-unref" title="g_object_unref ()">g_object_unref</a></code> |
| function call is made, a lot of things happen as described in |
| <a class="xref" href="gobject-memory.html#gobject-destruction-table" title="Table 5. g_object_unref">Table 5, “g_object_unref”</a>. |
| </p> |
| <p> |
| The destruction process of your object might be split in two different |
| phases: dispose and the finalize. |
| </p> |
| <pre class="programlisting"> |
| #define MAMAN_BAR_GET_PRIVATE(obj) (G_TYPE_INSTANCE_GET_PRIVATE ((obj), MAMAN_TYPE_BAR, MamanBarPrivate)) |
| |
| struct _MamanBarPrivate |
| { |
| GObject *an_object; |
| |
| gchar *a_string; |
| }; |
| |
| G_DEFINE_TYPE (MamanBar, maman_bar, G_TYPE_OBJECT); |
| |
| static void |
| maman_bar_dispose (GObject *gobject) |
| { |
| MamanBar *self = MAMAN_BAR (gobject); |
| |
| /* |
| * In dispose, you are supposed to free all types referenced from this |
| * object which might themselves hold a reference to self. Generally, |
| * the most simple solution is to unref all members on which you own a |
| * reference. |
| */ |
| |
| /* dispose might be called multiple times, so we must guard against |
| * calling g_object_unref() on an invalid GObject. |
| */ |
| if (self->priv->an_object) |
| { |
| g_object_unref (self->priv->an_object); |
| |
| self->priv->an_object = NULL; |
| } |
| |
| /* Chain up to the parent class */ |
| G_OBJECT_CLASS (maman_bar_parent_class)->dispose (gobject); |
| } |
| |
| static void |
| maman_bar_finalize (GObject *gobject) |
| { |
| MamanBar *self = MAMAN_BAR (gobject); |
| |
| g_free (self->priv->a_string); |
| |
| /* Chain up to the parent class */ |
| G_OBJECT_CLASS (maman_bar_parent_class)->finalize (gobject); |
| } |
| |
| static void |
| maman_bar_class_init (MamanBarClass *klass) |
| { |
| GObjectClass *gobject_class = G_OBJECT_CLASS (klass); |
| |
| gobject_class->dispose = maman_bar_dispose; |
| gobject_class->finalize = maman_bar_finalize; |
| |
| g_type_class_add_private (klass, sizeof (MamanBarPrivate)); |
| } |
| |
| static void |
| maman_bar_init (MamanBar *self); |
| { |
| self->priv = MAMAN_BAR_GET_PRIVATE (self); |
| |
| self->priv->an_object = g_object_new (MAMAN_TYPE_BAZ, NULL); |
| self->priv->a_string = g_strdup ("Maman"); |
| } |
| </pre> |
| <p> |
| </p> |
| <p> |
| Add similar code to your GObject, make sure the code still builds |
| and runs: dispose and finalize must be called during the last unref. |
| </p> |
| <p> |
| It is possible that object methods might be invoked after dispose is |
| run and before finalize runs. GObject does not consider this to be a |
| program error: you must gracefully detect this and neither crash nor |
| warn the user. |
| </p> |
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