[Qt-interest] = 0 ?

[Jeroen De Wachter]

Idd, this provides an equivalent to abstract classes/methods in Java

On Tue, 2010-02-23 at 12:34 +0000, Stephen Collyer wrote:
> On 23 February 2010 12:26, Lucas Pereira Caixeta <lpcnew at gmail.com>
> wrote:
>         
>         Hi all,
>         
>         In my interface i have this method: virtual String getName ()
>         = 0;    
>         
>         why this method have  "=0" in the end?
>         so that it serves?
>         
> This has nothing to do with Qt. It's a C++ feature. When you declare
> a method with = 0, you are creating a class that can't be
> instantiated.
> This is called a pure virtual method.
> 
> You can only use this class as as a base of another class, and you
> must
> provide a definition of the pure virtual method to be able to
> instantiate the
> class. 
> 
> The reason this is useful is that it allows a designer to create a
> class which
> specifies the interface of a class, but which doesn't provide all the
> functionaltity itself.
>  
> -- 
> Stephen Collyer
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