def create_animal(name):
 if name == 'dog':
  return Dog()
 elif name == 'cat':
  return Cat()

animal = create_animal('dog')
animal.eat('some food')

def create_operator(op):
 if op == '+':
  return AddOperation()
 elif op == '-':
  return SubOperation()
 elif op == '*':
  return MulOperation()
 elif op == '/':
  return DivOperation()

op = create_operator('+')
op.Calc(1, 2)

#encoding=utf-8 
# 
#by panda 
#简单工厂模式 
 
class OperateBase(): 
 result = 0; 
 def GetResult(self): 
  return self.result; 
 
class OperationAdd(OperateBase): 
 def __init__(self, NumA, NumB): 
  self.result = NumA + NumB; 
 def GetResult(self): 
  return self.result;   
  
class OperationSub(OperateBase): 
 def __init__(self, NumA, NumB): 
  self.result = NumA - NumB; 
 def GetResult(self): 
  return self.result; 
  
class OperationMult(OperateBase): 
 def __init__(self, NumA, NumB): 
  self.result = NumA * NumB; 
 def GetResult(self): 
  return self.result; 
 
class OperationDiv(OperateBase): 
 def __init__(self, NumA, NumB): 
  self.result = NumA / NumB; 
 def GetResult(self): 
  return self.result; 
 
class OperationFactory(): 
 @staticmethod 
 def createOperate(operate, NumA, NumB): 
  optList = { 
  '+':OperationAdd, 
  '-':OperationSub, 
  '*':OperationMult, 
  '/':OperationDiv,   
  } 
  oper = OperateBase() 
  if(optList.has_key(operate)): 
   oper = optList[operate](NumA, NumB);   
  return oper 
 
 
def clientUI(): 
 opt = raw_input("please input a operation(+-*/): "); 
 NumA = raw_input("please input the first number: "); 
 NumB = raw_input("please input the second number: ");  
 oper = OperationFactory.createOperate(opt, float(NumA), float(NumB)) 
 print "Restlt: ", oper.GetResult() 
 return 
 
if __name__ == '__main__': 
 clientUI();