Abstract Base Classes compatible with Python 2 and 3

5duj7z.py

#!/usr/bin/env python

# Abstract Base Classes compatible with Python 2 and 3.
# https://www.reddit.com/r/learnpython/comments/5duj7z/started_my_first_python_project_ever_need_help/

import abc

ABC = abc.ABCMeta('ABC', (object,), {})


class Base(ABC):
    @abc.abstractmethod
    def missing(self):
        pass


class MissingImplementations(Base):
    pass


class MyImplementedClass(Base):
    def missing(self):
        pass


if __name__ == "__main__":
    for clazz in [MyImplementedClass, MissingImplementations, Base]:
        print("Attempting to create %s" % clazz)
        assert issubclass(clazz, Base)
        try:
            c = clazz()
            print("OK: %s" % c)
        except TypeError as e:
            print("TypeError: %s" % e)


"""
$ python3.5 5duj7z.py 
Attempting to create <class '__main__.MyImplementedClass'>
OK: <__main__.MyImplementedClass object at 0x1014172e8>
Attempting to create <class '__main__.MissingImplementations'>
TypeError: Can't instantiate abstract class MissingImplementations with abstract methods missing
Attempting to create <class '__main__.Base'>
TypeError: Can't instantiate abstract class Base with abstract methods missing

$ python2.7 5duj7z.py
Attempting to create <class '__main__.MyImplementedClass'>
OK: <__main__.MyImplementedClass object at 0x10ec56210>
Attempting to create <class '__main__.MissingImplementations'>
TypeError: Can't instantiate abstract class MissingImplementations with abstract methods missing
Attempting to create <class '__main__.Base'>
TypeError: Can't instantiate abstract class Base with abstract methods missing
"""