import abc

class OrmSubject(metaclass=abc.ABCMeta):
    @abc.abstractmethod
    def addObserver(self, ormObserver):
        pass

    @abc.abstractmethod
    def removeObserver(self, ormObserver):
        pass

    @abc.abstractmethod
    def notify(self, subject):
        pass

class Observer(metaclass=abc.ABCMeta):
    @abc.abstractmethod
    def update(self, subject):
        pass

class BaseOrm(OrmSubject):

    def __init__(self):
        self.__observers = []

    def addObserver(self, ormObserver):
        print("Added: {0}".format(ormObserver))
        self.__observers.append(ormObserver)

    def removeObserver(self, ormObserver):
        self.__observers.remove(ormObserver)

    def notify(self, object):
        for observer in self.__observers:
            observer.update(object)

    @property
    def id(self):
        return self.__id

    @id.setter
    def id(self, id):
        notify = True
        try:
            old = self.id
            notify = False
        except AttributeError as e:
            pass
#            print(e)
#            notify = False
        self.__id = id
        if notify:
            self.notify(self)