observer pattern

# class Subscriber:
#     def __init__(self,name):
#         self.name = name
#     def update(self,message):
#         print('{} got message: {}'.format(self.name,message))
#
# class Publisher:
#     def __init__(self):
#         self.subscribers=set()
#     def register(self,who):
#         self.subscribers.add(who)
#     def unregister(self,who):
#         self.subscribers.discard(who)
#     def dispatch(self,message):
#         for subscriber in self.subscribers:
#             # update is a def in subscriber
#             subscriber.update(message)
#
# pub=Publisher()
#
# bob = Subscriber('Bob')
# alice = Subscriber('Alice')
# john = Subscriber('John')
#
# pub.register(bob)
# pub.register(alice)
# pub.register(john)
#
# pub.dispatch('Its lunchtime')
# pub.unregister(john)
# pub.dispatch('Its dinner time')


# class SubscriberOne:
#     def __init__(self,name):
#         self.name = name
#     def update(self,message):
#         print('{} got message: {}'.format(self.name,message))
#
#
# class SubscriberTwo:
#     def __init__(self,name):
#         self.name = name
#     def receive(self,message):
#         print('{} receive message: {}'.format(self.name, message))
#
# class Publisher:
#     def __init__(self):
#         self.subscribers = dict()
#     def register(self,who,callback=None):
#         if callback == None:
#             callback = getattr(who,'update')
#         self.subscribers[who]=callback
#         # one two  receive/// update
#
#     def unregister(self,who):
#         del self.subscribers[who]
#
#     def dispatch(self,message):
#         for subscriber, callback in self.subscribers.items():
#             callback(message)
#
# pub = Publisher()
# bob = SubscriberOne('Bob')
# alice = SubscriberTwo('Alice')
# john = SubscriberOne('John')
#
#
# pub.register(bob,bob.update)
# pub.register(alice,alice.receive)
# pub.register(john)
#
#
#
# pub.dispatch("It's lunchtime!")
# pub.unregister(john)
# pub.dispatch("Time for dinner")


a=['lunch', 'dinner']
b={event:dict() for event in a}
print(b)


class Subscriber:
    def __init__(self,name):
        self.name = name
    def update(self,message):
        print('{} got message {}'.format(self.name,message))

class Publisher:
    def __init__(self,events):
        self.events = {event: dict() for event in events}

    def get_subscribers(self,event):
        return self.events[event]

    def register(self,event,who,callback=None):
        if callback == None:
            callback = getattr(who, 'update')
        self.get_subscribers(event)[who]=callback

    def unregister(self,event,who):
        del self.get_subscribers(event)[who]

    def dispatch(self,event,message):
        for subscriber, callback in self.get_subscribers(event).items():
            callback(message)


pub = Publisher(['lunch','dinner'])
bob = Subscriber('bob')
alice = Subscriber('Alice')
john = Subscriber('John')

### can  distribute the message
pub.register('lunch',bob)
pub.register("lunch", john)
pub.register("dinner", john)

pub.dispatch("lunch", "It's lunchtime!")
pub.dispatch("dinner", "Dinner is served")


class Publisher:
    def __init__(self,customer_class):
        self.customer_class = {status: dict() for status in customer_class}

    def get_subscribers(self,status):
        return self.customer_class[status]

    def register(self,who,callback=None):
        if callback == None:
            callback = getattr(who, 'update')

        self.get_subscribers('promotion')[who] = callback

        if who.status=='VIP':
            self.get_subscribers('VIP promotion')[who]=callback


    def unregister(self,event,who):
        del self.get_subscribers(event)[who]

    def dispatch(self,event,message):
        for subscriber, callback in self.get_subscribers(event).items():
            callback(message)


class Subscriber:
    def __init__(self,name,status=None):

        self.name = name
        if status == None:
            self.status = 'Normal'
        else:
            self.status = status

    def update(self,message):
        print('{} customer {} got message {}'.format(self.status,self.name,message))


pub = Publisher(['VIP promotion','promotion'])
bob = Subscriber('bob','VIP')
alice = Subscriber('Alice')
john = Subscriber('John')
print(pub.customer_class)

### can  distribute the message
pub.register(bob)
pub.register(john)
pub.register(john)

pub.dispatch("VIP promotion", "It's VIP promotion!")
pub.dispatch("promotion", "it's promotion")