可选参数后的重载 [英] overload following optional argument

问题描述

我有一个类 Animal 和一个方法 foo 根据一个布尔参数 inplace 有不同的返回类型，它跟在一个可选参数 <代码>条形.我想重载该函数，以便在 inplace 的值已知时返回类型是已知的

I have a class Animal with a method foo which has different return types according to a boolean parameter inplace which follows an optional parameter bar. I'd like to overload the function so that the return type is known if the value of inplace is known

这是我的代码:

# main.py

from __future__ import annotations

from typing import Optional, overload, Literal 


class Animal:
    @overload
    def foo(self, bar=..., inplace: Literal[False]=...) -> Animal:
        ...

    @overload
    def foo(self, bar=..., inplace: Literal[True]=...) -> None:
        ...

    def foo(
        self, bar=None, inplace: bool = False
    ) -> Optional[Animal]:
        ...


reveal_type(Animal().foo(bar='a'))
reveal_type(Animal().foo(inplace=True))
reveal_type(Animal().foo(inplace=False))

$ mypy main.py
main.py:8: error: Overloaded function signatures 1 and 2 overlap with incompatible return types
main.py:21: note: Revealed type is 'main.Animal'
main.py:22: note: Revealed type is 'None'
main.py:23: note: Revealed type is 'main.Animal'
Found 1 error in 1 file (checked 1 source file)

https://mypy-play.net/?mypy=latest&python=3.9&gist=49da369f6343543769eed2060fa61639

如何避免第 8 行的 重载函数签名 1 和 2 与不兼容的返回类型重叠 错误?

How can I avoid the Overloaded function signatures 1 and 2 overlap with incompatible return types error on line 8?

推荐答案

这似乎有效:

from __future__ import annotations

from typing import Optional, overload, Literal 


class Animal:

    # using defaults
    @overload
    def foo(self, bar=..., inplace: Literal[False]=...) -> Animal: ...

    # using inplace = True
    
    # with bar
    @overload
    def foo(self, bar, inplace: Literal[True]) -> None: ...

    # without bar
    @overload
    def foo(self, *, inplace: Literal[True]) -> None: ...

    # with bool
    @overload
    def foo(self, bar=..., inplace: bool=...) -> Optional[Animal]: ...

    def foo(
        self, bar=None, inplace = False
    ):
        ...


reveal_type(Animal().foo(bar='a'))
reveal_type(Animal().foo(bar='a', inplace=True))
reveal_type(Animal().foo(bar='a', inplace=False))
reveal_type(Animal().foo(inplace=True))
reveal_type(Animal().foo(inplace=False))
reveal_type(Animal().foo())

inplace: bool
reveal_type(Animal().foo(bar='a', inplace=inplace))
reveal_type(Animal().foo(inplace=inplace))

很多重载，但也许这是不可避免的

Lots of overloads, but perhaps that's inevitable here

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