大話設計模式（1）—簡單工廠模式

Operation運算類別

# -*- coding: utf-8 -*-
class Operation(object):
 
    def __init__(self):
        self._numberA = 0
        self._numberB = 0
 
    @property
    def numberA(self):
        return self._numberA
 
    @numberA.setter
    def numberA(self, value):
        self._numberA = value

    @property
    def numberB(self):
        return self._numberB
     
    @numberB.setter
    def numberB(self, value):
        self._numberB = value
     
    def get_result(self):
        #result = 0
        #return result
        raise NotImplementedError
 

加減乘除類別

# -*- coding: utf-8 -*-
from operation import Operation

class DivZeroException: pass

class OperationAdd(Operation):
 
    def get_result(self):
        result = 0
        result = self._numberA + self._numberB
        return result
 
class OperationSub(Operation):
 
    def get_result(self):
        result = 0
        result = self._numberA - self._numberB
        return result
 
class OperationMul(Operation):
 
    def get_result(self):
        result = 0
        result = self._numberA * self._numberB
        return result
 
class OperationDiv(Operation):
 
    def get_result(self):
        result = 0
        if self._numberB == 0:
            raise DivZeroException
        result = self._numberA * 1.0 / self._numberB
        return result

簡單運算工廠類別

# -*- coding: utf-8 -*-
from suboperation import OperationAdd, OperationSub, OperationMul, OperationDiv

class OperationFactory:
 
    @staticmethod
    def create_operate(operate):
        oper = None
        if operate:
            if operate == '+':
                oper = OperationAdd()
            elif operate == '-':
                oper = OperationSub()
            elif operate == '*':
                oper = OperationMul()
            elif operate == '/':
                oper = OperationDiv()
        return oper        

用戶端程式碼

# -*- coding: utf-8 -*-
from operation import Operation
from operationfactory import OperationFactory

oper = OperationFactory.create_operate('+')
oper.numberA = 1
oper.numberB = 2
result = oper.get_result()
print result