Re: macro IS_xxx

[Andrea Zagli <azagli inwind it>]

Il giorno dom, 24/06/2007 alle 10.32 +0200, David Nečas (Yeti) ha
scritto:
> 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.

i need it because i pass obj_a/obj_b to a function that do different
things based on object type

is there a different way to make it without check the object type?

> > is it a bug? or is it normal?
> 
> Show me a single object system implementation that behaves
> differently in this regard...

i don't know... but i'm not an expert of oop