Re: GTK function to test whether GETWidget is a button/edit/columned list/whatever

["David Necas (Yeti)" <yeti physics muni cz>]

On Sat, Oct 23, 2004 at 02:40:29PM -0600, Neil Zanella wrote:
> Thanks,
>
> I see there are lots of macros in GTK. As a matter of fact I was just wondering
> what the difference is between:
>
> (GtkWidget *) foo and GTK_WIDGET(foo)
>
> and so on for such GTK_WINDOW, G_OBJECT, etc... kind of macros.
>
> Thanks,
>
> Neil
>
>
> On Sat, 23 Oct 2004 22:05:11 +0200, David Necas (Yeti)
> <yeti physics muni cz> wrote:
> > On Sat, Oct 23, 2004 at 01:47:34PM -0600, Neil Zanella wrote:
> > > I wonder whether GTK has a function to test a given widget to see
> > > whether it is a
> > > button/edit/columned list/whatever.
> >
> > GTK_IS_BUTTON(widget)
> > GTK_IS_EDITABLE(widget)
> > GTK_IS_...(widget)

For normal classes, GTK_FOO(bar) ends up as (GtkFoo*)bar,
except it checks if the cast is possible (this can be
disabled).

If GtkFoo is an interface (GtkFoo*)bar is simply wrong (the
pointer must be offset to point to the interface).

The moral is to always use GTK_FOO().

Yeti


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