What is proper way to require a method to be overridden?

[Bruno Desthuilliers]

Carl Banks a écrit :
> jeremito wrote:
> 
>>I am writing a class that is intended to be subclassed.  What is the
>>proper way to indicate that a sub class must override a method?
> 
> 
> You can't (easily).
> 
> If your subclass doesn't override a method, then you'll get a big fat
> AttributeError when someone tries to call it.

"override" implies that the method is already defined in one of the 
parent classes. So there's no reason for an AttributeError here...

(snip)