python 设计模式之
Vistor 模式：Vistor 模式常常用于将访问数据，支持传入不同的数据访问器（或是处理器），上例子
def visit(directory, visitor): for root, dirs, files in os.walk(directory): for f in files: ext = os.path.splitext(f)[-1] if hasattr(visitor,ext): a = getattr(visitor,ext) a(f)class FileReader(object): """ File Reader """ def bmp(self,f): print "is bmc",f visit("d:\\eastmoney\\",FileReader())is bmc btclose.bmpis bmc btclose2.bmpis bmc btclosedown.bmpis bmc btmax.bmp
Observer 模式：
Observer 模式常常用于侦听对象发生的变化，上例子
class Event(object): _observers = [] def __init__(self, subject): self.subject = subject @classmethod def register(cls, observer): if observer not in cls._observers: cls._observers.append(observer) @classmethod def unregister(cls, observer): if observer in cls._observers: self._observers.remove(observer) @classmethod def notify(cls, subject): event = cls(subject) for observer in cls._observers: observer(event) class WriteEvent(Event): def __repr__(self): return 'WriteEvent' def log(event): print '%s was written' % event.subject WriteEvent.register(log)WriteEvent.notify('a given file')
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