Multiple functions arguements to be friendly with MyPy

[fatrybl]

Hello!
I saw many discussions about MyPy friendly dispatching. But none of them answer the question:
how to dispatch a function with variable number of positional arguments s.t. MyPy wont blame on it ?
i saw this issue
and the instruction here
but there are equal number of arguments in overloaded methods and one needs to type annotate all of them in "dispatch". whereas in my case i have variable number of args in methods. So the final "dispatch" method can not handle this.
If i do not annotate any args in final "dispatch" method, MyPy also blames

for example:

from plum import dispatch, overload

@overload
def f(x: int) -> int:
    return x + 1

@overload
def f(x: str) -> str:
    return x

@overload
def f(x: str, y: str) -> str:
    return x + y

@dispatch
def f(x):
    raise NotImplementedError

Sorry, maybe i skipped an answer somehow, but is there a solution ?

[wesselb]

Hey @fatrybl!

I think you've forgotten to let the implement accept y:

from plum import dispatch, overload


@overload
def f(x: int) -> int:
    return x + 1


@overload
def f(x: str) -> str:
    return x


@overload
def f(x: str, y: str) -> str:
    return x + y


@dispatch
def f(x, y=None):
    raise NotImplementedError

This checks out with mypy on my end.

[fatrybl]

Thank you @wesselb ! So the idea is to list all the args anyway but they can be set to None. It works in my PyCharm with latest MyPy as well

[wesselb]

@fatrybl That’s exactly right! Glad to hear that it works for you. :)