Python 可变参数数量的重载类型(args或kwargs)

发布于04月16日

示例如下，需要确保IDE类型判断器或reveal_type能够正确识别k、j和i类型.

也许有某种方法可以建议输入args是空的tuple，kwargs是空的dict，那么返回值就是tuple[int]？

from typing import Union, overload

def test(*args: int, **kwargs: str) -> Union[int, str, tuple[int]]:
    if args:
        return 5
    if kwargs:
        return "5"
    return (5,)


# now all are Union[int, str, tuple[int]]
k = test(1)
j = test(i="1")
i = test()

reveal_type(k) # should be int
reveal_type(j) # should be str
reveal_type(i) # should be tuple[int]

推荐答案

这是一个可能的解决方案，允许mypy推断k、j和i的正确类型.这种方法确实会导致mypy抱怨过载签名重叠.我不确定除了简单地 suppress 错误之外是否还有可能解决这个问题.

from typing import Union, overload


@overload
def test() -> tuple[int]:  # type: ignore[overload-overlap]
    ...
    
@overload
def test(*args: int) -> int:  # type: ignore[overload-overlap]
    ...
    
@overload
def test(**kwargs: str) -> str:
    ...

def test(*args: int, **kwargs: str) -> Union[int, str, tuple[int]]:
    if args:
        return 5
    if kwargs:
        return "5"
    return (5,)


# now all are Union[int, str, tuple[int]]
k = test(1)
j = test(i="1")
i = test()

reveal_type(k) # should be int
reveal_type(j) # should be str
reveal_type(i) # should be tuple[int]

mypy --strict v1.9.0(try it online!)的输出:

main.py:29: note: Revealed type is "builtins.int"
main.py:30: note: Revealed type is "builtins.str"
main.py:31: note: Revealed type is "tuple[builtins.int]"
Success: no issues found in 1 source file