type_api.py 文件源码

def _type_affinity(self):
        """Return a rudimental 'affinity' value expressing the general class
        of type."""

        typ = None
        for t in self.__class__.__mro__:
            if t in (TypeEngine, UserDefinedType):
                return typ
            elif issubclass(t, (TypeEngine, UserDefinedType)):
                typ = t
        else:
            return self.__class__