@Scout Why is

mypy

failing?

from dagster import Config

class MyAssetConfig(Config):
    person_name: str

Metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

It appears that you're encountering an issue with

mypy

when using the

Config

class from Dagster. According to an issue reported on the Dagster Github repository, this problem arises from a metaclass conflict when using

dagster.Config

with

mypy

. The error message you're seeing indicates that

mypy

is having trouble with the metaclass of the derived class

MyAssetConfig

because it must be a subclass of the metaclasses of all its bases, which in this case includes

dagster.Config

. The issue report suggests that this problem stems from a difference in behavior between

mypy

and

pyright

regarding the understanding of the type of

ModelMetaclass

. The Dagster team is aware that they use

pyright

, which did not show metaclass errors in the codebase for the example provided in the issue. However,

mypy

does not seem to handle the situation in the same way. While the issue is at the type-checker level, the reporter of the issue was wondering if there's something that could be done within the Dagster codebase to unblock

mypy

users. The issue is still open, indicating that it might not have been resolved yet. For more details, you can refer to the specific Github issue: [Mypy raises error when using

dagster.Config

in Dagster 1.5.5](https://github.com/dagster-io/dagster/issues/17443). As a workaround, you might consider using

pyright

for type checking if that's an option for you, or you could follow the discussion on the issue tracker for updates and potential fixes from the Dagster team.