methoddispatch.py

from functools import singledispatch, wraps


class Foo(object):

    @singledispatch
    def foo(self, arg):
        print('called original')
    
    @foo.register(int)
    def _(self, arg):
        print('called dispatched')


f = Foo()
f.foo('hoge')  # called original
f.foo(770)  # called original


def methoddispatch(method):
    method = singledispatch(method)

    @wraps(method)
    def over(self, *args, **kwargs):
        return method.dispatch(type(args[0]))(self, *args, **kwargs)

    over.__dict__ = method.__dict__
    return over


class Bar(object):

    @methoddispatch
    def bar(self, arg):
        print('called original')
    
    @bar.register(int)
    def _(self, arg):
        print('called dispatched')


f = Bar()
f.bar('hoge')  # called original
f.bar(770)  # called dispatched