如何在python中枚举嵌套类？

Question

How to implement function, which enumerate nested classes?

class A(object):
    class B(object):
        pass

    class C(object):
        pass


def enumerate_nested_classes(_class):
    return ()  # need proper implementation instead


assert set(enumerate_nested_classes(A)) == {A.B, A.C}

Answer 1

inspect.getmembers() in conjunction with inspect.isclass() should help here:

classes = [name for name, member_type in inspect.getmembers(A)
           if inspect.isclass(member_type) and not name.startswith("__")]

print(classes)  # prints ['B', 'C']

^{Note that not name.startswith("__") check is needed to exclude __class__ - I suspect there is a simpler and a more pythonic way to do so, would appreciate if somebody would point that out.}

Answer 2

You can use the next code:

import types


class A(object):
    class B(object):
        pass

    class C(object):
        pass

def enumerate_nested_classes(_class):
    return [getattr(_class, n) for n in dir(_class) if not n.startswith('__')
            and isinstance(getattr(_class, n), (type, types.ClassType))] 

assert enumerate_nested_classes(A) == [A.B, A.C]

And print enumerate_nested_classes(A) prints [<class '__main__.B'>, <class '__main__.C'>]

NB. dir(_class) resulting list is sorted alphabetically, so when using assert enumerate_nested_classes(A) == [AB, AC] it is better to use: assert sorted(enumerate_nested_classes(A)) == sorted([AB, AC]) .