python / python/cpython

Doc string for locals() partly contradicts the full documentation

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還沒有人認領這個 Issue。

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描述

locals() documentation

>>> print(locals.__doc__)
Return a dictionary containing the current scope's local variables.

NOTE: Whether or not updates to this dictionary will affect name lookups in
the local scope and vice-versa is *implementation dependent* and not
covered by any backwards compatibility guarantees.

But in the docs:

At module scope, as well as when using exec() or eval() with a single namespace [...]

At class scope [...]

When using exec() or eval() with separate local and global arguments [...]

In all of the above cases, each call to locals() in a given frame of execution will return the same mapping object. Changes made through the mapping object returned from locals() will be visible as assigned, reassigned, or deleted local variables, and assigning, reassigning, or deleting local variables will immediately affect the contents of the returned mapping object.

In an optimized scope (including functions, generators, and coroutines), each call to locals() instead returns a fresh dictionary containing the current bindings of the function’s local variables and any nonlocal cell references. In this case, name binding changes made via the returned dict are not written back to the corresponding local variables or nonlocal cell references, and assigning, reassigning, or deleting local variables and nonlocal cell references does not affect the contents of previously returned dictionaries.

So either:

  • Behaviour is undefined and the full documentation fails to mention this in giving a complete description of it
  • The behaviour given in the full documentation is stable and can be relied upon, in which case the doc string is misleading

It feels like at least one of the two should be corrected/clarified.

Linked PRs
  • gh-127225

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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。

研究方向

先查看 locals() 的 docstring 輸出和連結的 PR gh-127225,然後將其與文件中 locals() 項目的描述進行比較。確定哪種措辭能夠準確涵蓋列出的作用域情況。完成的標準是 docstring 與完整文件不再相互矛盾。

由索引模型根據 Issue 內容生成。

評估

技術堆疊
python
領域
documentation
Issue 類型
文件
難度
2/5
預估耗時
1-3 小時
活躍度
停滯
描述清晰度
基本清楚
新手友好度
30/100

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