How to use a type defined later for function annotations?

Question

The problem is like this:

class A():
    def foo() -> B:
        pass

class B():
    def bar() -> A:
        pass

This will raise a NameError: name 'B' is not defined.

For the sake of type checking, I'm not willing to change -> B to -> "B". Is there any workaround?

Answer 1

I found a workaround, which is much similar to C or C++.

Tested in Pycharm 3.

class A: pass
class B: pass

class A(object):

    def foo(self, b: B) -> B:

        #CAN auto complete
        b.bar()

        return B()

class B(object):

    def bar(self) -> A:

        return A()

#CAN auto complete
A().foo(B()).bar()