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asyncio.events.BaseDefaultEventLoopPolicy gone from Python 3.14 without prior deprecation #131148
Closed as not planned
Description
Bug report
Bug description:
from asyncio.events import BaseDefaultEventLoopPolicyThis is from https://github.com/MagicStack/uvloop/blob/7bb12a174884b2ec8b3162a08564e5fb8a5c6b39/uvloop/__init__.py#L6 cc @fantix
On Python 3.13, this works.
On Python 3.14 since #128216 this no longer works and raises ImportError. As far as I know, the class was not deprecated in 3.13 or 3.12.
>>> from asyncio.events import BaseDefaultEventLoopPolicy
Traceback (most recent call last):
File "<python-input-0>", line 1, in <module>
from asyncio.events import BaseDefaultEventLoopPolicy
ImportError: cannot import name 'BaseDefaultEventLoopPolicy' from 'asyncio.events' (/usr/lib64/python3.14/asyncio/events.py)The commit message of #128216 does not mention any API removals at all. It has no NEWS either, so I assume this removal was accidental.
CPython versions tested on:
3.14, CPython main branch
Operating systems tested on:
Linux
Activity
Workaround missing BaseDefaultEventLoopPolicy in Python 3.14
picnixz commentedon Mar 12, 2025
I'm not sure this was meant to actually be publicly exposed. Policies were deprecated since 3.12 and
asyncio.events.BaseDefaultEventLoopPolicyhas probably not been intended to be public (I can't find it documented anywhere). cc @kumaraditya303Note that it's not really gone, just that it has been now named as really "private" (but maybe it should have been kept half-public?)
hroncok commentedon Mar 12, 2025
As a workaround,
from asyncio.events import _BaseDefaultEventLoopPolicycurrently works, indeed.I realize this was probably never meant to be a public API. It just kinda was.
kumaraditya303 commentedon Mar 12, 2025
BaseDefaultEventLoopPolicyis an undocumented and private class of a private submodule of asyncio. Only the stuff exposed from toplevel asyncio and that is documented is considered public.uvloop should change its code to not use private class and instead use abstract policy class.
picnixz commentedon Mar 12, 2025
Yes, it's something we had a lot in Sphinx where we named private objects with public names and didn't document them / export them, making them implicitly private, but not everyone assumes this kind of convention, which then makes refactoring usually breaking.
As for whether the lack of a changelog entry, it has been added afterwards (#128269 and #128290)
kumaraditya303 commentedon Mar 28, 2025
Closing as it is wont-fix
Fix test_loop_auto for Python 3.14
Fix test_loop_auto for Python 3.14
Workaround missing BaseDefaultEventLoopPolicy in Python 3.14
CPython 3.14-3.16 compat