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Type checking for *args and **kwargs when passing them to another function

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#2,036 10 comments 4 reactions 0 assignees View on GitHub

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
32/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
tooling

Research direction

Start with the wrapper and inner-function examples in the issue, then read the linked mypy#19302 discussion for the existing proposal and constraints. Done should be a documented, agreed approach for deriving or declaring wrapper argument types from the function or constructor receiving *args and **kwargs.

Written by the indexing model from the issue text.

Description

topic: feature

Problem:

I am writing a python application, and I made a function that creates an object and passes its additional *args and **kwargs to object's constructor and takes few its own arguments. I want to make *args and **kwargs typed exactly as inner function's arguments.

Description and examples:

A simple example with two functions:

def inner(a: int, b: int) -> None:
    ...


def wrapper(arg1: str, *args, **kwargs) -> None:
    inner(*args, **kwargs)  # It will automatically detect passing arguments to another function

In my case, inner is object constructor, I gave an example with functions to make it more simple.

Type checkers should see wrapper's signature like this:

def wrapper(arg1: str, a: int, b: int):
    ...

It may be enabled by default when passing *args and **kwargs to another function is detected or it may be enabled by adding a decorator to the function.

Detailed description:

Already suggested this to mypy, detailed description of this feature can be found here: python/mypy#19302.

Dominant language
Python
Stars
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Forks
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Avg merge
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Merged PRs (30d)
8

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