Hacktoberfest 2026：維護者為十月標記出來的 issue，仍然開放、適合新手。 瀏覽 Hacktoberfest issue

Clarify the valid use locations of `typing.Concatenate`

未關閉
  • 哪裡不對？
#2,140 2 則留言 0 個 reaction 已指派 0 人 在 GitHub 檢視

維護者通常 1 天內回覆

還沒有人認領這個 Issue。

評估

難度
4/5
預估耗時
3-5 天
新手友好度
38/100
Issue 類型
文件
描述清晰度
基本清楚
活躍度
停滯
技術堆疊
python
領域
documentation

研究方向

從 typing 規範的使用者定義泛型類別部分和 CPython 關於 typing.Concatenate 的文件開始，然後比較 mypy、pyright 和 ty 的範例及回報的行為。檢視連結的 Concatenate 搜尋筆記，並確定哪些使用位置有效；完成的標準是 typing 規範和 CPython 文件清楚地描述支援的形式以及巢狀 Concatenate 限制。

由索引模型根據 Issue 內容生成。

描述

topic: documentation

In python/cpython#142965, it was reported that the documentation of typing.Concatenate is "incorrect" (documentation that originates back to python/cpython#24000).

@A5rocks, in your example, Concatenate[int, P_2] somewhat finally lands as a first argument to Callable, just indirectly.
This snippet previously defined:

P_2 = ParamSpec("P_2")

class X(Generic[T, P]):
  f: Callable[P, int]
  x: T

Similar example is included in the typing spec:

https://typing.python.org/en/latest/spec/generics.html#user-defined-generic-classes

class X[T, **P]:
    f: Callable[P, int]
    x: T

# (...)
def accept_concatenate[**P](x: X[int, Concatenate[int, P]]) -> str: ...  # Accepted

However, it seems that the current situation (confirmed with mypy, pyright and ty) is that you can use Concatenate in all valid locations of ParamSpec except directly in a Concatenate. I.e., you can't do Concatenate[int, Concatenate[str, P]]), but you can (besides passing Concatenate form as the first argument to Callable):

  1. Accumulate Concatenates as ParamSpecs
from collections.abc import Callable
from typing import Concatenate

type Y[**P] = Callable[Concatenate[int, P], None]
type X[**P] = Y[Concatenate[int, P]]

def foo(f: X[str]) -> None:
    reveal_type(f)
    # mypy: def (builtins.int, builtins.int, builtins.str)
    # pyright: (int, int, str) -> None
    # ty: (...) -> None
  1. Bind Concatenates to user-defined generics as ParamSpecs
class X[T, **P]:
    f: Callable[P, int]
    x: T

def accept_concatenate[**P](x: X[int, Concatenate[int, P]]) -> str: ...
  1. Use Concatenate as a type argument to tuple -- is this correct?
from typing import Concatenate

def c(t: tuple[Concatenate[int, ...]]) -> None:
    reveal_type(c)
    # mypy: def (t: tuple[[builtins.int, *Any, **Any]])
    # pyright: (t: tuple[Concatenate[int, ...]]) -> None
    # ty: def c(t: tuple[@Todo]) -> None

I've found this mostly by poking around -- I haven't analyzed the actual implementations (yet).
I'll continue to investigate this from these searches.

I think that the valid use locations of Concatenate should be clarified in the typing spec and then in the CPython docs.

Is there anything else I overlooked? CC @JelleZijlstra @AlexWaygood

主要語言
Python
星號
1.8k
分支
302
平均合併
20 小時 26 分鐘
30 天內合併 PR
10

環境準備

我們還沒有檢查這個專案的環境設定檔。先看它的 README，通用步驟見我們的新手貢獻指南。

從這裡開始

  1. 先讀完整個 Issue，再讀專案的貢獻指南。
  2. 在 Issue 下留言說明你要接手 —— 這能避免兩個人做同樣的事。
  3. Fork 儲存庫，在一個分支上完成修改。
  4. 送出 Pull Request，並在描述裡引用這個 Issue 編號。

python/typing 的其他 Issue

查看 python/typing 的全部 Issue

相似的 Issue

更多 Python Issue

把新 issue 寄到你的電子郵件信箱

精選適合新手參與的 GitHub issue 摘要。