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typing an init parameter causes wrong argument calculation #4290
Description
I've got a class which has a method that creates instances of the class.
class Bar:
@classmethod
def create(cls, foo: int):
return cls(foo)
def __init__(self, foo: int) -> None:
pass
When I run mypy against it, it says mypytest.py:4: error: Too many arguments for "Bar"
It seems like a bug to me, because this works fine
class Bar:
@classmethod
def create(cls, foo):
return cls(foo)
def __init__(self, foo: int) -> None:
pass
I don't understand why a class method which defines the type of a parameter should break the creation of an instance.
Activity
gvanrossum commentedon Nov 29, 2017
This is because mypy processes definitions in order, and when it comes across
create()in the first version it hasn't seen the__init__()signature yet. IIRC there's another issue open for this.JelleZijlstra commentedon Nov 29, 2017
Yes, this is #1727.
mvoitko commentedon Oct 12, 2020
The same problem remains with SQLAlchemy models.