New submission from Julian Fortune <juliandfort...@gmail.com>:
I believe [`bpo-44806: Fix __init__ in subclasses of protocols`](https://github.com/python/cpython/pull/27545) has caused a regression when using a Dataclass. In Python `3.9.7`, a `dataclass` that inherits from a subclass of `typing.Protocol` (i.e., a user-defined protocol), does not have the correct `__init__`. ### Demonstration ```python from dataclasses import dataclass from typing import Protocol class P(Protocol): pass @dataclass class B(P): value: str print(B("test")) ``` In `3.9.7`: ```shell Traceback (most recent call last): File "test.py", line 11, in <module> print(B("test")) TypeError: B() takes no arguments ``` In `3.9.6`: ```shell B(value='test') ``` ### Affected Projects - [dbt](https://github.com/dbt-labs/dbt/issues/3843) ---------- components: Library (Lib) messages: 400868 nosy: julianfortune priority: normal severity: normal status: open title: dataclasses that inherit from Protocol subclasses have wrong __init__ type: behavior versions: Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue45081> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
