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observer.py
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observer.py
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import abc
class Observer:
__metaclass__ = abc.ABCMeta
def __init__(self, n, nr):
self.name = n
self.notifier = nr
@abc.abstractmethod
def update(self):
"""updated by notifier"""
class NbaObserver(Observer):
def update(self):
print self.name + ", " + self.notifier.state + ", close NBA"
class StockObserver(Observer):
def update(self):
print self.name + ", " + self.notifier.state + ", close stock"
class Notifier:
def __init__(self):
self.observers = []
self.state = ""
def attach(self, o):
self.observers.append(o)
def detach(self, o):
self.observers.remove(o)
def notify(self):
for observer in self.observers:
observer.update()
class Boss(Notifier):
pass
class Secretary(Notifier):
pass
if __name__ == "__main__":
boss = Boss()
nba_observer = NbaObserver("Bob", boss)
boss.attach(nba_observer)
stock_observer = StockObserver("Alice", boss)
boss.attach(stock_observer)
boss.state = "boss's back himself"
boss.notify()