Python 自动注册子类

class BaseMetaClass(type):

    record_cls = []

    def __iter__(self):

        return iter(BaseMetaClass.record_cls)

    def __new__(cls, name, bases, attrs):

        new_cls = type.__new__(cls, name, bases, attrs)

        if name != 'Base':

            BaseMetaClass.record_cls.append(name)

        return new_cls

class Base(object, metaclass=BaseMetaClass):

    pass