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[mypyc] Fixing __init__ for classes with @attr.s(slots=True). by advait-dixit · Pull Request #18447 · python/mypy · GitHub
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Fixes mypyc/mypyc#1079.

@attr.s generates a __init__ function which was getting lost in CPyDataclass_SleightOfHand. This change copies the generated __init__ function and a couple of others ones to maintain consistency with CPython.

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Thanks for the PR! I have one suggestion.

}
Py_DECREF(res);
// These attributes are added or modified by @attr.s(slots=True).
const char * const keys[] = {"__attrs_attrs__", "__attrs_own_setattr__", "__init__", ""};
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What about doing this only when using @attr.s, but not for a regular dataclass? E.g. pass a flag to the function indicating whether we are dealing with an attrs class.

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If my understanding is correct, CPython actually uses res but CPyDataclass_SleightOfHand(...) is throwing it away. So, copying attributes will probably reduce errors. Anyway, I have added a condition to copy attributes only for attr and attr-auto dataclasses. Please take a look.

@advait-dixit advait-dixit changed the title Fixing __init__ for classes with @attr.s(slots=True). [mypyc] Fixing __init__ for classes with @attr.s(slots=True). Jan 16, 2025
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Thanks for the update.

@JukkaL JukkaL merged commit c61bce4 into python:master Jan 17, 2025
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@advait-dixit advait-dixit deleted the fix_attr_slots branch January 21, 2025 22:01
x612skm pushed a commit to x612skm/mypy-dev that referenced this pull request Feb 24, 2025
…#18447)

Fixes mypyc/mypyc#1079.

`@attr.s` generates a `__init__` function which was getting lost in
`CPyDataclass_SleightOfHand`. This change copies the generated
`__init__` function and a couple of others ones to maintain consistency
with CPython.
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AttributeError with attr.s(slots=True)

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