callable virtual method

[MRAB]

Jean-Michel Pichavant wrote:
> Hi fellows,
> 
> Does anyone know a way to write virtual methods (in one virtual class) 
> that will raise an exception only if called without being overridden ?
> Currently in the virtual method I'm checking that the class of the 
> instance calling the method has defined that method as well.
> 
> Example:
> 
> class Stream(object):
>    """Interface of all stream objects"""
>    def resetStats(self):
>        """Reset the stream statistics. All values a zeroed except the 
> date."""
>        _log.info('Reset statistics of %s' % self)
>        if self.__class__.resetStats == Stream.resetStats:
>            raise NotImplementedError()
> 
> It works but it's tedious, I have to add these 2 lines to every virtual 
> method, changing the content of the 2 lines.
> 
> Maybe there is a nice/builtin way to do so (python 2.4)
> 
Why are you checking which class it's in? The method in the base class
will be called only if it hasn't been overridden in the subclass.