Breaks marshmallow_dataclass.NewType

[gabor-akeero]

In is_new_type there is an explicit check for the module name being either typing or typing_extensions, so types created via marshmallow_dataclass.NewType are no longer recognised, and therefore cannot be used in marshmallow dataclasses.

This check on __module__ makes it impossible to define and use any custom NewType implementations, even if they are intended to be accepted as NewType.

As the pre-3.10 implementations of typing.NewType define only two extra attributes __name__ and __supertype__, I'd suggest a check on these two (besides __qualname__), and on their types:

... isinstance(getattr(tp, '__supertype__', None), type) and isinstance(getattr(tp, '__name__'), str) and ...

This would check everything that we can be sure of, and wouldn't block the custom NewType-implementations.

[vit-zikmund]

@gabor-akeero it's questionable whether this needs to be fixed here (although an optional is_new_type parameter for a list of external modules that would also match could be nice). As marshmallow_dataclass.NewType virtually uses the exact pre 3.10 typing.NewType peppered with a couple more attributes, I think a nicer solution might be to use the typing.NewType and monkeypatch the resulting object, which doesn't change the original intention but makes it more independent on whatever happens in the typing (or a tightly related) module.

[vit-zikmund]

FYI, my fix for marshmallow_dataclass has been cherry-picked into lovasoa/marshmallow_dataclass#211 and merged to master. Unless reverted, the fix fill will be available with any next release (which I have no control of, tho).

[dairiki]

FYI, my fix for marshmallow_dataclass has been cherry-picked into lovasoa/marshmallow_dataclass#211 and merged to master. Unless reverted, the fix fill will be available with any next release (which I have no control of, tho).

A release has just been made of marshmallow-dataclass 8.5.9 that includes @vit-zikmund’s fixes for marshmallow_dataclass.NewType.

[gabor-akeero]

This issue has been fixed at marshmallow_dataclass