class DecorateMe(object):
    def __init__(self, foo=None):
        self.foo = foo

    def __call__(self, func):
        def wrapper(decorated_self, *args):
            return func(decorated_self, self.foo, *args)
        return wrapper

class Whatever(object):
    @DecorateMe(42)
    def b(self, *args):
        print self, args

Whatever().b('a', 'b', 'c')