Re: gtk-2 bug, inconsistency or simply misunderstanding on my side ?

[Owen Taylor <otaylor redhat com>]

Olivier Fourdan <fourdan xfce org> writes:

> Hi Owen,
>
> > How are you removing it? What do you mean by "freed twice"?
> > Can you provide a small test case?
>
> The container is removed with gtk_widget_destroy. By "freed twice", I
> mean that the widget destroy routine "mywidget_destroy(GtkObject
> *object)" is called twice, usually leading to a core dump.
>
> The gtkdial widget, given as example in gtk+-2.0.x source tree should be
> enough to see the problem, by adding a simple trace to
> gtk_dial_destroy() every time it's called.

destroy() does not mean "free", and having destroy() called
multiple times _will_ happen in some cases in GTK+-2.0. 
the finalize() method is called exactly once when the
object is being freed.

_destroy() means "break existing links between objects". 
_finalize() means free.

See:

http://developer.gnome.org/dotplan/porting/ar01s11.html#type-changes

So, yes, the gtkdial example is buggy:

  if (dial->adjustment)
    g_object_unref (GTK_OBJECT (dial->adjustment));

Should be 

  if (dial->adjustment)
    {
      g_object_unref (GTK_OBJECT (dial->adjustment));
      dial->adjustment = NULL;
    }

[ Filed as http://bugzilla.gnome.org/show_bug.cgi?id=94361 ]

Regards,
                                        Owen