Python 3 Object-Oriented Programming - Third Edition

Creating an abstract base class

As we saw earlier, it's not necessary to have an abstract base class to enable duck typing. However, imagine we were creating a media player with third-party plugins. It is advisable to create an abstract base class in this case to document what API the third-party plugins should provide (documentation is one of the stronger use cases for ABCs). The abc module provides the tools you need to do this, but I'll warn you in advance, this utilizes some of Python's most arcane concepts, as demonstrated in the following block of code::

import abc 
 
class MediaLoader(metaclass=abc.ABCMeta):    @abc.abstractmethod    def play(self):        pass    @abc.abstractproperty    def ext(self):        pass    @classmethod    def __subclasshook__(cls, C): if ...