python / python/typeshed

How to use _typeshed.wsgi with typing.get_type_hints

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描述

Hello there,
is there a way to get to work combination of _typeshed.wsgi and typing.get_type_hints in runtime?
In flask codebase there is something like

from __future__ import annotations

import typing as t

if t.TYPE_CHECKING:  # pragma: no cover
    from _typeshed.wsgi import WSGIApplication  # noqa: F401
    from werkzeug.datastructures import Headers  # noqa: F401
    from werkzeug.sansio.response import Response  # noqa: F401

# The possible types that are directly convertible or are a Response object.
ResponseValue = t.Union[
    "Response",
    str,
    bytes,
    t.List[t.Any],
    # Only dict is actually accepted, but Mapping allows for TypedDict.
    t.Mapping[str, t.Any],
    t.Iterator[str],
    t.Iterator[bytes],
]

# the possible types for an individual HTTP header
# This should be a Union, but mypy doesn't pass unless it's a TypeVar.
HeaderValue = t.Union[str, t.List[str], t.Tuple[str, ...]]

# the possible types for HTTP headers
HeadersValue = t.Union[
    "Headers",
    t.Mapping[str, HeaderValue],
    t.Sequence[t.Tuple[str, HeaderValue]],
]

# The possible types returned by a route function.
ResponseReturnValue = t.Union[
    ResponseValue,
    t.Tuple[ResponseValue, HeadersValue],
    t.Tuple[ResponseValue, int],
    t.Tuple[ResponseValue, int, HeadersValue],
    "WSGIApplication",
]

https://github.com/pallets/flask/blob/3.0.0/src/flask/typing.py
and in my application I use something like

from flask.typing import ResponseReturnValue

@inject
def my_endpoint() -> ResponseReturnValue:
    return "asdf"

...
def inject(method):
    ...
    arg_types = typing.get_type_hints(method)
    # get args from DI container and call actual function with injected args

which ends with error like

NameError: name 'Response' is not defined

Here is complete playground for my issue https://www.online-python.com/AsZX867MEO

I can probably use my own type for that - that's why I ask here - but not sure how to use typeshed in runtime.
Then I can probably send PR directly to flask with fix for such edge cases (as nobody probably encountered this based on how long this is in flask already).

Thanks for you tips and help in advice.

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  1. 先读完整个 Issue,再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库,在一个分支上完成修改。
  4. 提交 Pull Request,并在描述里引用这个 Issue 编号。

调研方向

从 Flask 的 src/flask/typing.py 和 issue 中所示的 typing.get_type_hints 调用开始,然后使用链接的 playground 重现 NameError。确定运行时故障属于 Flask 还是 typeshed,并通过可复现的测试或示例记录一个具体的解决方案。

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技术栈
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领域
tooling
Issue 类型
缺陷
难度
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预计耗时
3-5 天
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