class EventDispatcher:
    def __init__(self):
        from weakref import WeakKeyDictionary
        self.listeners = WeakKeyDictionary()
        self.msgs = 0

    def register(self, l):
        self.listeners[ l ] = 1

    def unregister(self, l):
        self.listeners.pop(l)

    def post(self, e):
        if isinstance(e, TickEvent):
            print "Message count : ", self.msgs
            self.msgs = 0
        else:
            self.msgs += 1

        for l in self.listeners.keys():
            l.notify(e)


### Events

class Event:
    def __init__(self):
        pass

class TickEvent(Event):
    def __init__(self):
        pass

class SimulationStartedEvent(Event):
    def __init__(self, sim):
        self.sim = sim


class QuitEvent(Event):
    def __init__(self):
        pass

class EnvironmentBuiltEvent(Event):
    def __init__(self, env):
        self.env = env

class AgentPlacedEvent(Event):
    def __init__(self, agent):
        self.agent = agent

class AgentMoveRequest(Event):
    def __init__(self):
        pass

class AgentMovedEvent(Event):
    def __init__(self, agent):
        self.agent = agent

class AgentKillEvent(Event):
    def __init__(self, agent):
        self.agent = agent

class AgentAddEvent(Event):
    def __init__(self, agent):
        self.agent = agent

class ViewSlideRequest(Event):
    def __init__(self, dir):
        self.dir = dir

class MouseClickEvent(Event):
    def __init__(self, pos, button):
        self.pos = pos
        self.button = button