abstract-base-class

Abstract vs. Interface - separating definition and implemention in Delphi

What is the better approach for separating definition and implementation, using interfaces or abstract classes? I actually I don't like mixing reference counted objects with other objects. I imagine that this can become a nightmare when maintaining large projects. But sometimes I would need to derive a class from 2 or more classes/in...

Python ABCs: registering vs. subclassing

(I am using python 2.7) The python documentation indicates that you can pass a mapping to the dict builtin and it will copy that mapping into the new dict: http://docs.python.org/library/stdtypes.html#mapping-types-dict I have a class that implements the Mapping ABC, but it fails: import collections class Mapping(object): def __i...