Python之简单工厂模式实现

最近又看了下大话设计模式，决定用Python来试着实现下。

基础类

class OperationBase():
    """
    基础运算类
    """
    result = 0
    def GetResult(self):
        return self.result

继承类

class OperationAdd(OperationBase):
    """
    加法类，继承基础运算类
    """
    def __init__(self,numA,numB):
        self.result = numA + numB
    def GetResult(self):
        return self.result

class OperationSub(OperationBase):
    """
    减法运算类，继承基础运算类
    """
    def __init__(self,numA,numB):
        self.result = numA - numB
    def GetResult(self):
        return self.result

class OperationMult(OperationBase):
    """
    乘法运算类，继承基础运算类
    """
    def __init__(self,numA,numB):
        self.result = numA * numB
    def GetResult(self):
        return self.result

class OperationDiv(OperationBase):
    """
    除法运算类，继承基础运算类，通过被除数为0异常捕获控制被除数不能为0
    """
    def __init__(self,numA,numB):
        try:
            self.result = numA / numB
        except ZeroDivisionError:
            print "除数不能为0！！！"

    def GetResult(self):
        return self.result

#工厂类
class OperationFactor():
    @staticmethod
    def createOperate(operate,numA,numB):
        for case in switch(operate):
            if case('+'):
                oper = OperationAdd(numA,numB)
                break
            if case('-'):
                oper = OperationSub(numA,numB)
                break
            if case('*'):
                oper = OperationMult(numA,numB)
                break
            if case('/'):
                oper = OperationDiv(numA,numB)
                break
        return oper

if __name__ == '__main__':
    opt = raw_input("请输入一个运算操作符(+-*/)：")
    try:
        numA = float(raw_input("请输入第一个运算的数字："))
        numB = float(raw_input("请输入第二个运算的数字："))
    except ValueError:
        print "输入数字不对，请重新输入！"
        numA = float(raw_input("请输入第一个运算的数字："))
        numB = float(raw_input("请输入第二个运算的数字："))

    oper = OperationFactor.createOperate(opt,float(numA),float(numB))
    print "Result = ",oper.GetResult()

里面的case可以参考我另外一篇博客

http://www.cnblogs.com/ListenWind/p/4267517.html