Re: finalization issues (?)

Thank you so much, no more segfaults.

On Tue, 2002-11-12 at 02:07, Gediminas Paulauskas wrote:
> An, 2002-11-12 03:09, Jacob Perkins rašė:
> > I have my own GObject called SeahorseWidget, which contains a GladeXML,
> > plus some extra data.  I've hooked up the finalize function to free the
> > xml, then sets the xml to null.  To create a new dialog, I create a new
> > SeahorseWidget, which connect generic signals, such as when the cancel
> > button is pressed.  When the 'closed' signal calls g_object_unref on the
> > SeahorseWidget, which then causes finalize to be called.
> > The problem is that some dialogs can only have one instance at a time. 
> > I keep a static SeahorseWidget pointer in the dialog's source file.  To
> > check if an instance already exists, I check if the pointer is null, or
> > if pointer->xml is null.  If this does not fail, the I call
> > gtk_window_present(glade_xml_get_widget (swidget->xml, swidget->name)),
> > which gets the main window.  Unfortunately, the instance test does not
> > always fail when it should and I get segfaults from
> > glade_xml_get_widget.
> Which is expected behavior. When widget is destroyed, swidget points to
> invalid memory address, and you cannot check if swidget->xml is NULL. it
> can be anything.
> However, for such cases a special method was added to Glib 2:
> g_object_add_weak_pointer. When object is finalized, it sets that
> pointer to NULL. It means that a pointer is valid only when an object is
> alive. So, make it:
> void
> seahorse_generate_show (SeahorseContext *sctx)
> {	
> 	if (swidget != NULL) {
> 		gtk_window_present (GTK_WINDOW (glade_xml_get_widget (swidget->xml, swidget->name)));
> 		return;
> 	}
> 	swidget = seahorse_widget_new ("generate", sctx);
> 	g_object_add_weak_pointer (G_OBJECT (swidget), &swidget);
> -- 
> Gediminas
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> desktop-devel-list mailing list
> desktop-devel-list gnome org

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