Get PyCharm to know what classes are mixin for

Question

Our application has set of complex form wizards. To avoid code duplication I created several mixins.

The problem is that PyCharm highlights mixin methods with Unre

Answer 1

You can type-hint to PyCharm what kind of classes to expect.

class DictMixin(object):
    def megamethod(
        self,  # type: dict
        key
    ):
        return self.get(key)

It's still not quite comparable to other type handling. PyCharm is lazy in evaluating it, and only does so when first working on self. Things are a bit tricky when accessing attributes of the mixin as well - self, # type: dict | DictMixin works for one of my classes, but not in my test code. In python 3.5, you should be able to use # type: typing.Union[dict, DictMixin].