How can I check if a GtkWidget exists?
How can I check if a GtkWidget exists? I am planning to create and destroy widgets in a window depending on the user's selections, but I can't figure out how to determine if a particular widget already exists in the window so it won't be created twice or receive a second deletion attempt if it's already gone. I tried checking GTK_WIDGET_REALIZED but it appears that if the widget has previously been destroyed then the GTK_WIDGET_REALIZED tries to access it anyway and gives me an error. Is there a way to determine if a widget is already in a window without having to maintain my own table? -- MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com www.creekfm.com - FIFTY THOUSAND WATTS of POW WOW POWER! ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: How can I check if a GtkWidget exists?
On Fri, Jul 20, 2012 at 12:50:45AM -0600, Frank Cox wrote: How can I check if a GtkWidget exists? By keeping track of it (either when you create and destroy the widgets or using weak references/weak pointers/destroy callbacks/...). ‘Checking the existence of a widget’ is, essentially, a meaningless phrase. If the widget has been destroyed you do not have any means to *refer* to it. You cannot ask ‘does this widget exist’ because there is no way to say ‘this widget’. Using the pointer to the memory the widget used to occupy for anything is a programming error. Yeti ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: How can I check if a GtkWidget exists?
On 7/20/2012 8:50 AM, Frank Cox wrote: How can I check if a GtkWidget exists? I am planning to create and destroy widgets in a window depending on the user's selections, but I can't figure out how to determine if a particular widget already exists in the window so it won't be created twice or receive a second deletion attempt if it's already gone. I tried checking GTK_WIDGET_REALIZED but it appears that if the widget has previously been destroyed then the GTK_WIDGET_REALIZED tries to access it anyway and gives me an error. Is there a way to determine if a widget is already in a window without having to maintain my own table? Not sure, but perhaps GTK_IS_WIDGET (widget) macro would help. Miroslav ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: How can I check if a GtkWidget exists?
On Fri, Jul 20, 2012 at 10:15:54AM +0200, Miroslav Rajcic wrote: Not sure, but perhaps GTK_IS_WIDGET(widget) macro would help. If you have the pointer to a GObject instance and want to know whether it is an instance of GtkWidget (including subclasses) then GTK_IS_WIDGET() is the right thing to use. But if you use this macro with a random pointer (e.g. one pointing to a memory location where some GObject might be some time ago) do not expect anything more useful than a CRITICAL error/crash. To deal with objects that may or may not exist use one of the several mechanisms (weak pointers/weak refs/destroy callbacks/...) for keeping track of the object existence. And, generally, use these mechanisms to avoid even the possibility of dangling pointers in your code. Yeti ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re : How can I check if a GtkWidget exists?
Have you try g_object_add_weak_ref ? Weak references are used for notification when an object is finalized. Hope this helps. ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Re : How can I check if a GtkWidget exists?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 07/20/2012 11:54 AM, Nicolas SOUBEIRAN wrote: Have you try g_object_add_weak_ref ? Weak references are used for notification when an object is finalized. Hope this helps. The GTK_IS_WIDGET macro is useful as well. Kevin - -- Get my public GnuPG key from http://pgp.mit.edu:11371/pks/lookup?op=getsearch=0x7D0BD5D1 -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlAJnCUACgkQ6w2kMH0L1dECDACffj/EM0QcslT+mA43SQq7oWow C8AAniwfsDSk13n/RP7friOwX/aUk2qQ =ESuh -END PGP SIGNATURE- ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
