Subclass method not getting resolved

user_3574837 0
Viewed 59

I have the following structure:

import abc


class AbstractParent:
    pass

class AbstractChild(AbstractParent):
    @abc.abstractmethod
    def foo(self):
        raise NotImplementedError()

class Child(AbstractChild):
    def foo(self):
        print('!')

class A:
    def __init__(self, x: AbstractParent):
        self.x = x

class B(A):
    def __init__(self, x: Child):
        super().__init__(x=x)
    
    def test(self):
        return self.x.foo()      # Unresolved attribute reference 'foo' for class 'AbstractParent'

What I would expect is that since Child is a subclass of AbstractParent and Child has a method foo, and since x is being declared as a Child in class B, that foo is able to be resolved as a method of Child.

Instead Pycharm has a visual warning Unresolved attribute reference 'foo' for class 'AbstractParent' Why isn't it able to figure out that x is a Child which has method foo?

Note that setting self.x = x in B fixes the issue. Is this a bug?

type-hinting pycharm python
1 Answers

It could be solved with generics, see the following example:

from typing import Generic, TypeVar


T = TypeVar("T", bound=AbstractParent)


class A(Generic[T]):
    x: T
    
    def __init__(self, x: T):
        self.x = x


class B(A[Child]):
    def __init__(self, x):
        super().__init__(x=x)

    def test(self):
        return self.x.foo()

Feel free to ask any questions.

user_22356980
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