Description

brijkapadia

opened on Mar 3, 2026

Issue body actions

Feature or enhancement

Proposal:

After discussion on PR #145362, it became clear that there are many possibilities for unintended mutations in the partialobject in Module/_functoolsmodule.c, particularly for the kw dictionary for keywords. Thus, changing kw to be a frozendict could prevent any unintended consequences.

Additionally, right now, the keys of kw could be an arbitrary PyObject, leading to unintended code execution if they are not strings. Thus, enforcing that the entries are strings could solve any future problems (similar to what happened in #145362).

Lastly, Issue #145446 also makes sure that there are no unintended mutations in the functools internals for free-threading, but changing to using a frozendict would be a more robust solution.

I will work on this and create a PR in the next couple of days. I will wait until #145446 is resolved to avoid any conflicts.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

#145362 (comment)

Linked PRs

• gh-145478: Implement frozendict into functools.partial #145960

Activity

1. brijkapadia

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on Mar 3, 2026
2. StanFromIreland

   added

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   on Mar 3, 2026
3. rhettinger commented on Mar 3, 2026

   

   rhettinger

   on Mar 3, 2026

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   This sounds like a reasonable approach. Immutable dictionaries can provide early detection or prevention for a number of subtle problems, especially those arising from free-threading.

   Reacted by Brij Kapadia
4. brijkapadia commented on Mar 12, 2026

   

   brijkapadia

   on Mar 12, 2026

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   Update: While I was working on this issue, I found that it would be convenient to have a way to convert a frozendict to a dict since a normal keywords dictionary is needed when calling functions. As such, I am waiting to create a PR until #145531 is merged.
5. vstinner commented on Mar 12, 2026

   

   vstinner

   on Mar 12, 2026

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   it would be convenient to have a way to convert a frozendict to a dict

   Currently, you can use dict = PyObject_CallOneArg((PyObject*)&PyDict_Type, frozendict); which calls the dict constructor. In my PR gh-145531, I proposed adding PyAnyDict_AsNewDict() function for that.

   Reacted by Brij Kapadia
6. brijkapadia

   added a commit that references this issue on Mar 15, 2026

   pythongh-145478: Implement `frozendict` into `functools.partial`

   cdb948f
7. brijkapadia

   closed this as not plannedon Jun 1, 2026

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