abcplus

abcplus is an extended version of Python's stdlib abc module. It adds support for additional features that are sometimes useful with Abstract Base Classes.

It is meant to supplant abc, so it has a copy of all the symbols from the default abc package. So you can just do an import alias and not modify working code:

import abcplus as abc

Or you can import it directly if you want:

from abcplus import ABCMeta, abstractmethod, abstractproperty, finalmethod

@finalmethod

While it's rare, there are certain legitimate cases where you want to prevent a method from being overridden in subclasses. Some other languages have a final keyword for this case. This module adds an @finalmethod decorator which will prevent a subclass from declaring an overridden form of the method. There are workarounds that a developer could use to avoid this check, so don't consider this absolute protection against it, but somewhat stronger than a simple advisory comment.

# Python 2 example

import abcplus

class Abstract(object):

    __metaclass__ = abcplus.ABCMeta

    @abcplus.finalmethod
    def run(self):
        self.prepare()
        self.execute()
        self.cleanup()

    @abcplus.abstractmethod
    def execute(self):
        pass

    def prepare(self):
        pass

    def cleanup(self):
        pass

# Python 3 requires you to define the metaclass differently

import abcplus

class Abstract(object, metaclass=abcplus.ABCMeta):
    pass

# or use six to add the metaclass in a way that works with both

import abcplus
import six

@six.add_metaclass(abcplus.ABCMeta):
class Abstract(object):
    pass