A Mixin class for making class based plugins

plugin_subclasses.py

#!/usr/bin/env python3

class PluginSubclassesMixin:
    def __init_subclass__(cls, register_base=False, **kwargs):
        super().__init_subclass__(**kwargs)
        if PluginSubclassesMixin not in cls.__bases__:
            return

        cls.subclasses = []
        if register_base:
            cls.subclasses.append(cls)

        @classmethod
        def mixin_subclass_init(subcls, **kwargs):
            super(cls, subcls).__init_subclass__(**kwargs)
            cls.subclasses.append(subcls)

        cls.__init_subclass__ = mixin_subclass_init

class Stuffinators(PluginSubclassesMixin, register_base=True):
    pass


class Stuffluff(Stuffinators):
    pass

class Stufflargh(Stuffluff):
    pass


print("Stuffinators", Stuffinators.subclasses)
print("Stuffluff", Stuffluff.subclasses)
print("Stufflargh", Stufflargh.subclasses)