Re: gtk_widget_destroy, gtk_object_destroy

[Sven Neumann <sven gimp org>]

Esteban Quijano Vincenzi <Esteban Quijano artinsoft com> writes:

> What's the difference between gtk_widget_destroy and gtk_object_destroy? I
> guess every widget should be deallocated with gtk_widget_destroy and not
> with gtk_object_destroy, so, why there is no gtk_window_destroy,
> gtk_ctree_destroy, etc? Do they call a background destructor?

from gtkwidget.c:

void
gtk_widget_destroy (GtkWidget *widget)
{
  g_return_if_fail (widget != NULL);
  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (GTK_OBJECT_CONSTRUCTED (widget));

  gtk_object_destroy ((GtkObject*) widget);
}

so all you get with gtk_widget_destroy() is the additional 
GTK_IS_WIDGET (widget) check since gtk_object_destroy calls
g_return_if_fail (GTK_OBJECT_CONSTRUCTED (object)) again.
In short: there is no real difference.

> What are gtk_widget_ref and gtk_widget_unref for? How are them related to
> gtk_widget_destroy?

widget_ref and widget_unref increase and decrease the reference count
of the widget. If the reference count drops to zero, the widget is
destroyed. The gtk_widget_destroy() function is a wrapper that calls
gtk_object_destroy(). To fully understand gtk_object_destroy(), I'd 
suggest you read http://developer.gnome.org/doc/GGAD/cha-objects.html
and in particular http://developer.gnome.org/doc/GGAD/sec-finalization.html.
 
> Can we gtk_object_ref a widget and gtk_widget_unref it? Because it seems it
> is possible.

gtkwidget.h:#  define gtk_widget_unref gtk_object_unref
gtkwidget.h:#  define gtk_widget_ref gtk_object_ref

these are just stupid wrappers around the gtk_object functions.

> Should we use gtk_widget_ref - gtk_widget_unref or gtk_object_ref -
> gtk_object_unref in every GTK program?

I suggest using the gtk_object variants only since you avoid to suffer
from serious brain damage by doing so. The wrappers are just making 
everything even more complicated. 

> When we call gtk_main_quit what happen to all deallocated widgets? Is it
> wrong to call gtk_widget_destroy after gtk_main_quit?

it shouldn't hurt since all signal functions are synchronous and do not
depend on the main loop running.


Salut, Sven