Create a generic python class from a rust struct.

[hoel-bagard]

Hi, I'm wondering if there is a way to make a generic python class using PyO3. I don't want to modify the rust code's behavior, my goal is to be able to write better type stubs for my package.

I would like to write stubs like this one:

from typing import Generic, TypeVar

T = TypeVar("T", int, str)

class MyClass(Generic[T]):
    my_var: T
    def __init__(self, my_var: T) -> None:
        ...

def concact_str(a: MyClass[str], b: MyClass[str]) -> str:
    ...

Which would allow a type checker to check cases like this one:

obj1 = MyClass("1")
obj2 = MyClass(2)

concact_str(obj1, obj2)  # Type checking says that this is not valid.

(My rust code is a struct with an Enum field, and some python functions do not have the same signature depending on the variant of the enum)

[hoel-bagard]

For anyone having the same issue, what I did is add the Generic in python and re-export the modified class (not sure if that's the best way to do it though):

from _mypackage import MyClass

from typing import Generic, TypeVar

T = TypeVar("T", int, str)

class MyClass(MyClass, Generic[T]):
    pass