Re: macro IS_xxx

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

On Sun, Jun 24, 2007 at 09:48:01AM +0200, Andrea Zagli wrote:
> i have GObject A and GObject B; B is a A's subclass
> 
> obj_a = a_new ();
> obj_b = b_new ();
> 
> (a_new() and b_new() return GObject)
> 
> when i call IS_OBJECT_A (obj_b) it returns TRUE: why?

Because obj_b *is* also an instance of A.  That's the
whole point of subclassing.

To check the exact type you can get it with
G_TYPE_FROM_INSTANCE and compare.  However, in most cases
needing this means there's something wrong with your design.

> is it a bug? or is it normal?

Show me a single object system implementation that behaves
differently in this regard...

Yeti

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