Python使用设计模式中的责任链模式与迭代器模式的示例

责任链模式

责任链模式：将能处理请求的对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理请求为止，避免请求的发送者和接收者之间的耦合关系。

#encoding=utf-8 
# 
#by panda 
#职责连模式 

def printInfo(info): 
  print unicode(info, 'utf-8').encode('gbk') 

#抽象职责类 
class Manager(): 
  successor = None 
  name = '' 
  def __init__(self, name): 
    self.name = name 

  def SetSuccessor(self, successor): 
    self.successor = successor 

  def HandleRequest(self, request): 
    pass 

#具体职责类：经理 
class CommonManager(Manager): 
  def HandleRequest(self, request): 
    if request.RequestType == '请假' and request.Number <= 2: 
      printInfo('%s:%s 数量%d 被批准' % (self.name, request.RequestContent, request.Number)) 
    else: 
      if self.successor != None: 
        self.successor.HandleRequest(request) 

#具体职责类：总监 
class Majordomo(Manager): 
  def HandleRequest(self, request): 
    if request.RequestType == '请假' and request.Number <= 5: 
      printInfo('%s:%s 数量%d 被批准' % (self.name, request.RequestContent, request.Number)) 
    else: 
      if self.successor != None: 
        self.successor.HandleRequest(request) 

#具体职责类：总经理 
class GeneralManager(Manager): 
  def HandleRequest(self, request): 
    if request.RequestType == '请假': 
      printInfo('%s:%s 数量%d 被批准' % (self.name, request.RequestContent, request.Number)) 
    elif request.RequestType == '加薪' and request.Number <= 500: 
      printInfo('%s:%s 数量%d 被批准' % (self.name, request.RequestContent, request.Number)) 
    elif request.RequestType == '加薪' and request.Number > 500: 
      printInfo('%s:%s 数量%d 再说吧' % (self.name, request.RequestContent, request.Number)) 

class Request(): 
  RequestType = '' 
  RequestContent = '' 
  Number = 0 

def clientUI(): 
  jinLi = CommonManager('金力') 
  zongJian = Majordomo('宗健') 
  zhongJingLi = GeneralManager('钟金利') 

  jinLi.SetSuccessor(zongJian) 
  zongJian.SetSuccessor(zhongJingLi) 

  request = Request() 
  request.RequestType = '请假' 
  request.RequestContent = '小菜请假' 
  request.Number = 1 
  jinLi.HandleRequest(request) 

  request.RequestType = '请假' 
  request.RequestContent = '小菜请假' 
  request.Number = 5 
  jinLi.HandleRequest(request) 

  request.RequestType = '加薪' 
  request.RequestContent = '小菜要求加薪' 
  request.Number = 500 
  jinLi.HandleRequest(request) 

  request.RequestType = '加薪' 
  request.RequestContent = '小菜要求加薪' 
  request.Number = 1000 
  jinLi.HandleRequest(request) 
  return 

if __name__ == '__main__': 
  clientUI(); 

类图：

迭代器模式
迭代器模式：提供一种方法顺序访问一个聚合对象中的各个元素，而又不暴露该对象的内部表示。

python内置支持这种模式，所以一般来说，不用自己写，

#encoding=utf-8 
# 
#by panda 
#迭代器(Iterator)模式 

def printInfo(info): 
  print unicode(info, 'utf-8').encode('gbk') 

#迭代器抽象类 
class Iterator: 
  def First(self): 
    pass 

  def Next(self): 
    pass 

  def IsDone(self): 
    pass 

  def CurrentItem(self): 
    pass 

#集合抽象类 
class Aggregate: 
  def CreateIterator(self): 
    pass 

#具体迭代器类： 
class ConcreteIterator(Iterator): 
  aggregate = None 
  current = 0 
  def __init__(self, aggregate): 
    self.aggregate = aggregate 
    self.current = 0 

  def First(self): 
    return self.aggregate[0] 

  def Next(self): 
    ret = None 
    self.current += 1 
    if(self.current < len(self.aggregate)): 
      ret = self.aggregate[self.current] 
    return ret 

  def IsDone(self): 
    if(self.current < len(self.aggregate)): 
      return False 
    else: 
      return True 

  def CurrentItem(self): 
    ret = None 
    if(self.current < len(self.aggregate)): 
      ret = self.aggregate[self.current] 
    return ret 

#具体集合类 
class ConcreteAggregate(Aggregate): 
  items = None 
  def __init__(self): 
    self.items = []     

def clientUI(): 
  a = ConcreteAggregate() 
  a.items.append('大鸟') 
  a.items.append('小菜') 
  a.items.append('行李') 
  a.items.append('老外') 
  a.items.append('公交内部员工') 
  a.items.append('小偷') 

  printInfo('---------迭代器模式-------------') 
  i = ConcreteIterator(a.items) 
  item = i.First() 
  while(False == i.IsDone()): 
    printInfo("%s 请买车票！" % i.CurrentItem()); 
    i.Next() 

  printInfo('n---------python内部迭代-------------') 
  for item in a.items: 
    printInfo("%s 请买车票！" % item); 
  return 

if __name__ == '__main__': 
  clientUI(); 

类图：