selfless.py

import inspect


class Selfless(type):
    def __new__(cls, name, bases, attrs):
        # Detect any methods without `self` as the first argument
        selfless_methods = {}
        for k, v in attrs.items():
            if callable(v):
                try:
                    args, vargs, kwargs, defaults = inspect.getargspec(v)
                    if not args or args[0] != 'self':
                        selfless_methods[k] = attrs.pop(k)
                except TypeError:
                    continue

        # Inject `self` as the first argument to selfless methods
        def selfless(g):
            return lambda self, *args, **kwargs: g(*args, **kwargs)

        # Set selfless methods as wrapped attributes
        new_class = type(name, bases, attrs)
        for k, f in selfless_methods.items():
            import ipdb; ipdb.set_trace()
            setattr(new_class, k, selfless(f))

        return new_class


class HelloWorld(object):
    __metaclass__ = Selfless

    def __init__(self, name):
        self.name = name

    def say_hello(self):
        print 'Hello, {}!'.format(self.name)

    def say_hello_world():
        print 'Hello, World!'

    def say_hello_to(name):
        print 'Hello, {}!'.format(name)


if __name__ == '__main__':
    hello = HelloWorld(name='Noah')

    hello.say_hello()
    hello.say_hello_world()
    hello.say_hello_to('Travis')