[Python] simple factory design pattern

# -*- coding:utf-8 -*-


class Operation(object):
    '''
    四则运算的父类,接收用户输入的数值
    '''
    def __init__(self, number1=0, number2=0):
        self.num1 = number1
        self.num2 = number2

    def GetResult(self):
        pass
    pass

#加法运算类
class OperationAdd(Operation):
    def GetResult(self):
        return self.num1 + self.num2

#减法运算类
class OperationSub(Operation):
    def GetResult(self):
        return self.num1 - self.num2

#乘法运算类
class OperationMul(Operation):
    def GetResult(self):
        return self.num1 * self.num2

#除法运算类
class OperationDiv(Operation):
    def GetResult(self):
        if self.num2 == 0:
            return '除数不能为0 '
        return 1.0*self.num1 / self.num2

#其他操作符类
class OperationUndef(Operation):
    def GetResult(self):
        return '操作符错误'

#简单工厂类
class OperationFactory(object):
    def choose_oper(self,ch):
        if ch == '+':
            return OperationAdd()
        elif ch == '-':
            return OperationSub()
        elif ch == '*':
            return OperationMul()
        elif ch == '/':
            return OperationDiv()
        else:
            return OperationUndef()

if __name__ == "__main__":
    ch = ''
    num1 = 2
    oper = '*'
    num2 = 1
    # Operation(num1,num2)
    OF = OperationFactory()
    oper_obj = OF.choose_oper(oper)
    oper_obj.num1 = num1
    oper_obj.num2 = num2
    print ('运算结果为: ',oper_obj.GetResult())

Reprinted from: https://www.cnblogs.com/onepiece-andy/p/python-simple-factory-pattern.html