I want to create a decorator that adds a member to the decorated class that is instance of outer class. In this case, decorator memberclass adds attribute self to the instance of class y that is of type X class memberclass[Y]: def __init__(self, cls: type[Y]): self.cls = cls def __get__(self, x, cls) -> Y | type[Y]: if x is None: return self.cls # I deleted some lines related to memorizing y per instance of X y = self.cls() y.self = x return y class X: z: int @memberclass class y: def f(self): # self.self is instace of X # type checker should be aware of self.self.z # X.y is class y # X().y is instance of that class # X().y.self is X() My best guess would be that there might be some way to annotate __get__ method to say "Y is getting a new member self with type typeof x". I checked whole documentation https://docs.python.org/3/library/typing.html and didn't find solution. This also didn't help How to type hint python magic __get__ method since it doesn't show how to modify type This also didn't help Is it possible to change method type annotations for a class instance? since it modifies function signature, but not the class members Continue reading...
