学步园

工厂模式的核心：

有这样一群类，他们区别很小，就像运算符类，他们的区别仅仅就是不同的运算符号。这样我们可以建一个工厂，按需“生产”出所需的所需要的类的实例。

#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();

UML类图如下：