装饰者模式

一、装饰者模式

图解

如何不依赖于Nokia类，直接用耳机类本身来返回实例。

二、示例代码

#include 

using namespace std;

class Phone
{
public:
    virtual int cost() = 0;
};

class Nokia : public Phone
{
public:
    virtual int cost()
    {
        return 5000;
    }
};

class DecoratePhone : public Phone
{
public:
    DecoratePhone(Phone* ph) : _phone(ph) {}

protected:
    Phone * _phone;
};

class ScreenProtecterPhone : public DecoratePhone
{
public:
    ScreenProtecterPhone(Phone *ph) : DecoratePhone(ph) {}

    virtual int cost()
    {
        return 100 + _phone->cost();
    }
};

class HeadSetPhone : public DecoratePhone
{
public:
    HeadSetPhone(Phone *ph) : DecoratePhone(ph) {}

    virtual int cost()
    {
        return 200 + _phone->cost();
    }
};

int main()
{
    Nokia nk;
    cout << nk.cost() << endl;

    ScreenProtecterPhone sp(&nk);
    cout << sp.cost() << endl;
    

//    ScreenProtecterPhone sp2(&sp);
//    cout << sp2.cost() << endl;

    HeadSetPhone hp(&sp);
    cout << hp.cost() << endl;

    Phone *p = new HeadSetPhone(new ScreenProtecterPhone(new HeadSetPhone(new ScreenProtecterPhone(new Nokia))));
    cout << p->cost() << endl;

    return 0;
}