大话设计模式--装饰模式 C++简单例子

装饰模式在对象动态增加功能方面优于继承，用装饰模式替代继承，比继承更加灵活。

小菜扮靓第三版

class person
{
public:
    virtual void show(){
        cout << "汤姆: " ;
    }
};

class decorator :public person
{
public:
    person *m_a;//被装饰者
    void decorate(person* a){
        m_a = a;
    }
    //void show(){
    //    if (m_a != nullptr){
    //        m_a->show();
    //    }
    //}
};

class Tshirt : public decorator
{
public:
    void show(){
        m_a->show();//被装饰者先执行
        cout << "T恤 ";
        //decorator::show();
    }
};

class shores : public decorator
{
public:
    void show(){
        m_a->show();
        cout << "鞋子 ";
        //decorator::show();
    }
};

int main()
{
    person *Tom=new person();
    Tshirt *Gucci=new Tshirt();
    shores *Vans=new shores();

    Gucci->decorate(Tom);//Gucci的m_a为person类
    Vans->decorate(Gucci);//Vans的m_a为Tshirt类
    Vans->show();

    return 0;
}

小菜扮靓第二版

class person
{
public:
    virtual void show(){}
};

class Tom : public person
{
public:
    void show(){
        cout << "汤姆: ";
    }
};
class Jerry : public person
{
public:
    void show(){
        cout << "杰瑞: ";
    }
};

class decorator :public person
{
public:
    person *m_a;
    void decorate(person* a){
        m_a = a;
    }
    //void show(){
    //    if (m_a != nullptr){
    //        m_a->show();
    //    }
    //}
};

class Tshirt : public decorator
{
public:
    void show(){
        m_a->show();
        cout << "T恤 ";
        //decorator::show();
    }
};

class shores : public decorator
{
public:
    void show(){
        m_a->show();
        cout << "鞋子 ";
        //decorator::show();
    }
};

int main()
{
    //person *tom = new Tom();
    //Tshirt *Gucci = new Tshirt();
    //shores *Vans = new shores();

    //Gucci->decorate(tom);
    //Vans->decorate(Gucci);
    //Vans->show();

    person *jerry = new Jerry();
    Tshirt *Gucci = new Tshirt();
    shores *Vans = new shores();

    Gucci->decorate(jerry);
    Vans->decorate(Gucci);
    Vans->show();
    return 0;
}