How do I get a reference to all classes implementing descriptor object in python

Question

I am creating a descriptor, and I want to create a list inside it that holds references to all objects implementing it, it is supposed to be some kind of a shortcut where I

Answer 1

If that's all your descriptor do, it's a bit of an abuse of the descriptor protocol. Just overriding your class __new__ or __init__ would be simpler:

class Foo(object):
    _instances = []

    def __new__(cls, *args, **kw):
        instance = object.__new__(cls)
        cls._instances.append(instance)
        return instance

    @classmethod
    def get_instances(cls):
        return self._instances