输入提示这是一个子类

Question

How does one indicate via type hints that one class is a subclass of another? Eg.

class Foo:
  def foo(self, x):
    pass

def dynamic() -> Type[Foo]:
  class SubFoo(Foo):
    pass

  return SubFoo

class SubSubFoo(dynamic()):
  def f|  # no suggestions from my editor

My editor (PyCharm) does not provide suggestions in the above case, indicating that static analysis does not recognize that SubSubFoo is a subtype of Foo . How can I use type hints to indicate this?

Answer 1

I have an answer from JetBrains indicating that this is a limitation of PyCharm rather than a limitation or misuse of type hints:

In this particular case it's IDE limitation, we don't look inside dynamic() function as it may be a lot more complex.

- Andrey Resler

As a fix, I am using an idiom where whenever I subclass dynamic() I will also subclass Foo after that, which leads to the desired suggestions appearing without altering the logic of the program (even if it does look a bit weird).