Ridiculous syntax for class creation with extra parameters in pure python

traits.py

"""
This is valid (but ridiculous) syntax:

spam_with_eggs = Spam<<'eggs'>>('ham', 'bacon')
"""


class _TraitAlias:
    __slots__ = ('__origin__', '__traits__')

    def __init__(self, cls, traits):
        self.__origin__ = cls
        self.__traits__ = traits

    def __call__(self, *args, **kwargs):
        raise SyntaxError("trait definition is missing the closing '>'")

    def __rshift__(self, args):
        print(
            f"{self.__origin__.__name__}"
            f"<<{','.join(map(repr, self.__traits__))}>>"
            f"({', '.join(map(repr, args))})"
        )

        # TODO: generic subscript [...]
        if isinstance(args, tuple):
            instance = self.__origin__(*args)
            instance.__origin_class__ = self
            instance.__origin__ = self.__origin__
            instance.__traits__ = self.__traits__
            return instance
        elif isinstance(args, list):
            if not len(args):
                raise SyntaxError('empty generics list')
            # wut, star expressions don't work for __class_getitem__?
            cls = self.__origin__[args[0] if len(args) == 1 else tuple(args)]
            return _TraitAlias(cls, self.__traits__)
        else:
            raise SyntaxError(f"'(' or '[' expected, got {args}")

    __gt__ = __rshift__


class TraitType(type):
    def __lshift__(cls, traits):
        _traits = traits if isinstance(traits, tuple) else (traits,)
        print('<', cls.__name__, traits)
        return _TraitAlias(cls, _traits)

    __lt__ = __lshift__


class Trait(metaclass=TraitType):
    ...


if __name__ == '__main__':
    class Spam(Trait):
        def __init__(self, *args):
            self.args = args
    
    
    spam = Spam<<'eggs'>>('ham', 'bacon')
    print("spam args:", spam.args)
    print("spam traits:", spam.__traits__)
    
    
    # to illustrate why used shifts instead of lt/gt:
    
    spam2 = Spam<'eggs'>('ham', 'bacon')
    print("spam2 args:", spam2.args)
    print("spam2 traits:", spam2.__traits__)