c++装饰者模式

1.装饰者模式简介

   装饰模式指的是在不必改变原类文件和使用继承的情况下，动态地扩展一个对象的功能。它是通过创建一个包装对象，也就是装饰来包裹真实的对象。

2.源码实现

#include <iostream>
#include <string>

using namespace std;

//抽象构件角色
class Phone
{
public:
    virtual void Show() = 0;
};

class iPhone : public Phone
{
public:
    iPhone(string strName) : m_strName(strName) {};
    ~iPhone() {};
    void Show()
    {
        cout << m_strName << endl;
    }

private:
    string m_strName;
};

class NokiaPhone : public Phone
{
public:
    NokiaPhone(string strName) : m_strName(strName) {};
    ~NokiaPhone() {};
    void Show()
    {
        cout << m_strName << endl;
    }

private:
    string m_strName;
};

//抽象装饰者角色
class Decorator : public Phone
{
public:
    Decorator(Phone *phone) : m_pPhone(phone) {};
    ~Decorator() {};
    virtual void Show()
    {
        m_pPhone->Show();
    }

private:
    Phone *m_pPhone;
};

class DecoratorPhoneA : public Decorator
{
public:
    DecoratorPhoneA(Phone *phone) : Decorator(phone) {};
    ~DecoratorPhoneA() {};
    void Show()
    {
        Decorator::Show();
        AddDecorator();     //添加新装饰
    }

private:
    inline void AddDecorator()
    {
        cout << "DecoratorPhoneA装饰" << endl;
    }
};

class DecoratorPhoneB : public Decorator
{
public:
    DecoratorPhoneB(Phone *phone) : Decorator(phone) {};
    ~DecoratorPhoneB() {};
    void Show()
    {
        Decorator::Show();
        AddDecorator();     //添加新装饰
    }

private:
    inline void AddDecorator()
    {
        cout << "DecoratorPhoneB装饰" << endl;
    }
};

int main(int argc, char **argv)
{
    //具体构件角色
    Phone *phone = new iPhone("iphone");

    if(phone == NULL)
    {
        return -1;
    }

    //具体装饰者角色
    Phone *pDePhone = new DecoratorPhoneA(phone);

    if(pDePhone == NULL)
    {
        delete phone;
        return -1;
    }

    pDePhone->Show();

    delete pDePhone;

    //具体装饰者角色
    pDePhone = new DecoratorPhoneB(phone);

    if(pDePhone == NULL)
    {
        delete phone;
        return -1;
    }

    pDePhone->Show();

    delete pDePhone;

    delete phone;

    return 0;
}

3.编译源码

$ g++ -o example example.cpp

4.运行及其结果

$ ./example
iphone
DecoratorPhoneA装饰
iphone
DecoratorPhoneB装饰