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

[Fuzzyman]

Carl Banks wrote:
> 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).
>

Well...

How about not defining it on the base class, but check in the
constructor that the attribute exists and that it is of type
FunctionType ?

Fuzzyman
http://www.voidspace.org.uk/python/articles.shtml