Python Function Overloading With MetaClasses (Terrible)

multiple_dispatch_metaclass.py

'''Script that impliments function overloading in python hatefully

Requires python 3.10, doesn't support kwargs for overloaded functions
'''
from inspect import get_annotations

class DispatchDict(dict):
    def __call__(self, *args, **kwargs):
        if len(self) == 1:
            # Hack for non-multiple dispatch functions
            return next(iter(self.values()))(self, *args, **kwargs)
        if kwargs:
            raise NotImplementedError('Add kwargs')

        call = tuple([type(arg) for arg in args])
        if call not in self:
            raise TypeError('Incorrect Args, maybe?')
        return self[call](self, *args)

class SetDispatchDict(dict):
    def __setitem__(self, key, value):
        if callable(value):
            dispatch = self.get(key, DispatchDict())
            dispatch[tuple(get_annotations(value).values())] = value
            value = dispatch
        super().__setitem__(key, value)
    
class DispatchMeta(type):
    @classmethod
    def __prepare__(cls, name, bases):
        return SetDispatchDict()

class Foo(metaclass=DispatchMeta):
    def what(self, a: int):
        print('int')

    def what(self, a: float):
        print('float')

    def what(self, a: int, b: int):
        print('int, int')

    def other_func(self, a):
        print(f'Single Dispatch with keyword arg: {a}')

if __name__ == '__main__':
    f = Foo()
    f.what(10)
    f.what(10.0)
    f.what(10, 10)
    f.other_func(a = 'Bupity')

'''Output
int
float
int, int
Single Dispatch with keyword arg: Bupity
'''