如何检查NewType值的类型？

发布于 2025-02-12 01:35:46 字数 1639 浏览 1 评论 0原文

如何在不铸造和混合类型检查的情况下检查newType的值 str ？

我声明了一种新类型：

BoardId = NewType("BoardId", str)

除str之外，我将其用作方法参数作为单个值或迭代。

我使用实例检查类型是否为str而不是tuple，然后我将其转换为元组，否则请按原样使用它。问题pyright事物boardId是str，因为isinstance失败了类型检查。另一方面，我不能使用isinstance newType以来

：

离开时

    async def get_stickies(
        self, board_id: Union[BoardId, Iterable[BoardId]]
    ) -> List[Sticky]:
        board_ids: Iterable[BoardId] = (
            (board_id,) if isinstance(board_id, str) else board_id
        )

要出现这个问题：

Diagnostics:                                                                                                                      
1. Expression of type "tuple[BoardId | str] | Iterable[BoardId]" cannot be assigned to declared type "Iterable[BoardId]"
     Type "tuple[BoardId | str] | Iterable[BoardId]" cannot be assigned to type "Iterable[BoardId]"
       TypeVar "_T_co@Iterable" is covariant
         Type "BoardId | str" cannot be assigned to type "BoardId"
           "str" is incompatible with "BoardId"

原文

How do you check the value of NewType against its basic type str without casting and mixing up type checking?

I declared a new type:

BoardId = NewType("BoardId", str)

that I use as a method parameter either as a single value or as an Iteration other than str.

I use instanceof to check if the type is str and not Tuple then I convert it to a tuple otherwise use it as it is.
The problem pyright things BoardId is str because of isinstance which fails the type checking.
On the other hand, I cannot use isinstance against NewType since:

TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union

Leaving as it is

    async def get_stickies(
        self, board_id: Union[BoardId, Iterable[BoardId]]
    ) -> List[Sticky]:
        board_ids: Iterable[BoardId] = (
            (board_id,) if isinstance(board_id, str) else board_id
        )

causes this issue:

Diagnostics:                                                                                                                      
1. Expression of type "tuple[BoardId | str] | Iterable[BoardId]" cannot be assigned to declared type "Iterable[BoardId]"
     Type "tuple[BoardId | str] | Iterable[BoardId]" cannot be assigned to type "Iterable[BoardId]"
       TypeVar "_T_co@Iterable" is covariant
         Type "BoardId | str" cannot be assigned to type "BoardId"
           "str" is incompatible with "BoardId"

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毁梦 2025-02-19 01:35:46

中提出了一种解决方案。

from typing import Iterable, TypeAlias, NewType

_BoardIdT: TypeAlias = str
BoardId = NewType('BoardId', _BoardIdT)

def get_stickies(board_id: BoardId | Iterable[BoardId]) -> None:
    board_ids: Iterable[BoardId] = (
        (board_id,) if isinstance(board_id, _BoardIdT) else board_id
    )

在

； mypy不喜欢此无证件属性。

One solution was proposed in this issue:

from typing import Iterable, TypeAlias, NewType

_BoardIdT: TypeAlias = str
BoardId = NewType('BoardId', _BoardIdT)

def get_stickies(board_id: BoardId | Iterable[BoardId]) -> None:
    board_ids: Iterable[BoardId] = (
        (board_id,) if isinstance(board_id, _BoardIdT) else board_id
    )

Playground link

The underlying type is accessible via BoardId.__supertype__, but mypy doesn't like this undocumented attribute.

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