class Actor(object):
    def __init__(self, name, speed):
        self.speed = speed
        # create the generator and bind the next method to self.update
        # so that whenever self.update() is called, it calls the next method
        # on the generator
        self.update = self._update().next   
        self.name = name

    def act(self):
        print "   >", self.name
        
    def _update(self):
        while True:
            for i in range(self.speed):
                yield None
            yield self.act   # return a reference which is called later

john = Actor("John", 5)
mary = Actor("Mary", 8)
goblin1 = Actor("Goblin1", 7)
goblin2 = Actor("Goblin2", 6)

actors = [john, mary, goblin1, goblin2]
for i in range(50):
    print "Turn",i+1
    for actor in actors:
        func = actor.update()
        if func:            # If actor.update() doesn't return None...
            func()          # call the function (ie self.act) it returns