Re: GObject Interface vs Pure Virtual Class

[Jean Bréfort <jean brefort normalesup org>]

Le samedi 12 mai 2007 �4:13 +0800, Kuang-Chun Cheng a �it :
> Sorry if you receive this twice, I send this to gtk-devel-list which I
> registered before,
> but somewhat my email to gtk-devel-list bounce back ...
> 
> 
> Hi,
> 
> I'm studying GObject system and found that I can implement both 
> Pure Virtual Class (by setting all member functions NULL to make the
> class pure virtual)
> and an Interface in GObject.
> 
> I'm a C programmer without much C++ experiences, but according 
> to my understanding ... pure virtual class in C++ is Interface.  Am I
> correct ?
> 
> My guess is, in GObject, provide extra API to implement an Interface
> is just another easier way to implement pure virtual class. 
> GObject interface will add more internal check which is better
> than just set the member function to NULL, but ... there are
> the same stuff, am I correct ?
> 
> Does any other good reason why GObject need an extra API set 
> for Interface ?
> 
> What's the different between Pure Virtual Class and Interface
> in GObject system ?

A GObject class can inherit from only one parent (which might be
virtual), but you can add as many Interfaces as you like. It is somewhat
similar to multiple inheritance in C++ (more like the D language
actually).

Jean

> Regards
> KC
> 
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-- 
Jean Br�rt <jean brefort normalesup org>