2.1.4　服装打折中的开闭原则

2.1.3小节已经完整描述了服装销售的步骤和UML类图，其中关键的类和类对应的方法也已经确定，接下来就是根据以上思路进行编程了。只要有了思路，编程是轻而易举的。为了让读者真正掌握一套程序设计的方法，在程序设计中真正做到开闭结合，下面分步来实现服装店打折的框架设计。

第一步：设计接口基类Clothes，声明派生类需要实现的虚方法。

#pragma once
#include <iostream>
using namespace std;
#include <cstring>
　
class Clothes
{
    public:
        //服装名称
        virtual string getClothesName()=0;
        //服装价格
        virtual int getClothesPrice()=0;
};

第二步：设计派生类SkirtClothes，并实现基类接口。

#include "clothes.h"
　
//SkirtClothes派生类
class SkirtClothes:public Clothes
{   
    public:
        SkirtClothes(){}
        SkirtClothes(string _name, int _price)
        {
            this->clothesname = _name;
            this->clothesprice = _price;
        }
　
        ~SkirtClothes(){}
　
        //对基类接口函数的实现
        string getClothesName(){return this->clothesname;}
        int getClothesPrice(){return this->clothesprice;}
　
    public:
        string clothesname;
        int clothesprice;
};

第三步：设计T恤打折后的派生类OffPriceSkirtClothes。

#include "skirtclothes.h"
　
//OffPriceSkirtClothes派生类
class OffPriceSkirtClothes:public SkirtClothes
{
    public:
       //不能用初始化列表的方式（派生类不能初始化基类中的成员变量）
        OffPriceSkirtClothes(string _name, int _price)
        {
            this->clothesname = _name;
            this->clothesprice = _price;
        }
        //重写覆盖基类的实现
        int getClothesPrice()
        {   
            
            offskirtprice=SkirtClothes::getClothesPrice();
            offskirtprice=offskirtprice*90/100;
            return offskirtprice;
        }
    private:
        int offskirtprice;
};

第四步：新增秋季服装类AutumnClothes，并声明自身类的虚接口。

#include "clothes.h"
　
//新增秋季服装类AutumnClothes及接口方法
class AutumnClothes:public Clothes
{   
    public:
        //AutumnClothes包含服装种类方法
        virtual string getAutumnClothesKinds()=0;
};

第五步：新增派生类SweaterAutumnClothes，实现Clothes、AutumnClothes的虚方法。

#include "autumnclothes.h"
　
//新增派生类SweaterAutumnClothes，继承自AutumnClothes
class SweaterAutumnClothes:public  AutumnClothes
{   
    public:
        SweaterAutumnClothes(){}
        SweaterAutumnClothes(string _name, int _price, string _kinds)
        {
            this->clothesname = _name;
            this->clothesprice = _price;
            this->clotheskinds = _kinds;
        }
        
        //对基类接口函数的实现
        string getClothesName(){return this->clothesname;}
        int getClothesPrice(){return this->clothesprice;}
        string getAutumnClothesKinds(){return this->clotheskinds;}
　
    public:
        string clothesname;
        int clothesprice;
        string clotheskinds;
};

第六步：设计客户端调用类函数，遵循开闭原则。

#include "offpriceskirtclothes.h"
#include "sweaterautumnclothes.h"
#include <list>
//一个管理所有服装类的集合
class ClothesStoreFromWenZhou
{
    public:
        ClothesStoreFromWenZhou(){}
        ~ClothesStoreFromWenZhou(){}
        //获取服装类集合
        void getClothes()
        {   
            for (int i=0;i<3;i++)
            {
                skirt_clotheslist.push_back(b1[i]);
                offpriceskirt_clotheslist.push_back(b2[i]);
                sweaterautumn_clotheslist.push_back(b3[i]);
            }
        }
        //服装销售
        void playClothes()
        {  
            //Skirt
            list<SkirtClothes>::iterator item1;
            for (item1= skirt_clotheslist.begin(); item1!= 
            skirt_clotheslist.end(); item1++)
            {
                  clothesname = item1->getClothesName();
                  clothesprice = item1->getClothesPrice();
                  cout<<"clothesname "<<clothesname<<" clothesprice: "<<
                  clothesprice<<endl;
            }
            
            //OffPriceSkirt
            list<OffPriceSkirtClothes>::iterator item2;    
            for (item2= offpriceskirt_clotheslist.begin(); 
            item2!=offpriceskirt_clotheslist.end(); item2++)
            {
                  clothesname = item2->getClothesName();
                  clothesprice = item2->getClothesPrice();
                  cout<<"clothesname "<<clothesname<<" clothesprice: "<<
                  clothesprice<<endl;
            }
            
            //AutumnClothes
            list<SweaterAutumnClothes>::iterator item3;   
            for (item3= sweaterautumn_clotheslist.begin(); 
            item3!=sweaterautumn_clotheslist.end(); item3++)
            {
                  clothesname = item3->getClothesName();
                  clothesprice = item3->getClothesPrice();
                  clotheskinds = item3->getAutumnClothesKinds();
                  cout<<"clothesname "<<clothesname<<" clothesprice: "<<
                  clothesprice<<" clotheskinds "<<clotheskinds<<endl;
            }
          
          }
     
   private:
        string clothesname;
        int clothesprice;
       
        //各类服装的定义及定价
        list<SkirtClothes> skirt_clotheslist;
        SkirtClothes b1[3]={
            SkirtClothes("男士Skirt",200),
            SkirtClothes("女士Skirt",600),
            SkirtClothes("小孩Skirt",100)
        };
　
        list<OffPriceSkirtClothes> offpriceskirt_clotheslist;
        OffPriceSkirtClothes b2[3]={
            OffPriceSkirtClothes("男士Skirt",200),
            OffPriceSkirtClothes("女士Skirt",600),
            OffPriceSkirtClothes("小孩Skirt",100)
        };
        string clotheskinds;
        list<SweaterAutumnClothes> sweaterautumn_clotheslist;
        SweaterAutumnClothes b3[3]={
            SweaterAutumnClothes("阿迪达斯Sweater",500,"Sweater"),
            SweaterAutumnClothes("李宁Sweater",600,"Sweater"),
            SweaterAutumnClothes("优衣库Sweater",300,"Sweater")
        };       
};
　
int main()
{   
    ClothesStoreFromWenzhou clothesfromwz;
    clothesfromwz.getClothes();
    clothesfromwz.playClothes();
　
    return 0;
}

结果显示：

clothesname男士Skirt clothesprice: 200
clothesname女士Skirt clothesprice: 600
clothesname小孩Skirt clothesprice: 100
clothesname男士Skirt clothesprice: 180
clothesname女士Skirt clothesprice: 540
clothesname小孩Skirt clothesprice: 90
clothesname阿迪达斯Sweater clothesprice: 500 clotheskinds Sweater
clothesname李宁Sweater clothesprice: 600 clotheskinds Sweater
clothesname优衣库Sweater clothesprice: 300 clotheskinds Sweater