#An event listener which registers with a Dispatcher which will assign it events of
#a appropriate type to handle
class Listener(object):
    def __init__(self, t):
        self.type = t
        self.registered = False

    def register(self, dispatcher):
        self.registered = True
        dispatcher.register_listener(self)

    def can_handle(self, event):
        if event.type == self.type:
            return True
        else:
            return False

    def handle_event(self, event):
        event.handle()

#An event dispatcher which will be passed events and find a listener to handle the event
class Dispatcher(object):
    def __init__(self):
        self.listeners = []
        self.numListeners = 0

    def get_numListeners():
        return self.numListeners

    def register_listener(self, listener):
        self.listeners.append(listener)
        numListeners += 1

    def dispatch_event(self, event):
        if get_numListeners == 0:
            print "Error, no listeners registered."
        else:
            for list in self.listeners:
                if list.can_handle(event):
                    list.handle_event(event)

        print "No listeners of event type are registered."


#An event object which will do a thing
class Event(object):
    def __init__(self, t):
        self.type = t
        handled = False
    def handle():
        handled = True

#Script which can be run to test out functionality for the event system
if __name__ == "__main__":

    #New listener
    listener = Listener(1)
    dispatcher = Dispatcher()

    #Registration
    listener.register(dispatcher)

    #Dispatch
    event = Event(1)
    dispatcher.dispatch_event(event)