[Hotfix] Make Use class callable to resolve mypy type errors with And/Or

[qequ]

When using Use with And or Or combinators, mypy reported a type error:

from schema import And, Use schema = And(int, Use(int))

Error:

Argument 2 to "And" has incompatible type "Use"; expected "Callable[..., Any]" 

Solution

Added __call__ method to the Use class, making it properly callable:

def __call__(self, data: Any) -> Any: return self._callable(data)

Closes #336

[skorokithakis]

Hmm, how did calling work before without the class being callable?

[qequ]

there was no call definition but this is mostly a static type check error in execution time there are no changes. the implementation of call seems more suitable given that is a wrapper of the callable being used but it could be left unimplemented and I think mypy would pass given that it would be callable

[skorokithakis]

Hmm, I'm confused. The proper way to use Use before this was to call it, no? How did that work without a call definition?

[qequ]

I don't think so given that the Use class has the validate method and that calls the callable method it wraps and in the _priority method its checked first that has the validate method than the it's callable (https://github.com/keleshev/schema/blob/master/schema/__init__.py#L335) Use class will always be used via validate method that's why didn't need the __call__ implementation

[skorokithakis]

Makes sense, thank you!