设计模式-备忘录模式

适用情境:在一个对象外部记录其状态,在对象状态改变后提供恢复以前状态的功能.

// device.h
#ifndef DEVICE_H
#define DEVICE_H

#include "memo.h"

class Device
{
public:
    Device();
    Memo* CreateMemo();
    void Recover(Memo* memo);
    void Show();
public:
    int m_state_code;
};

#endif // DEVICE_H

//device.cpp
#include "device.h"
#include <iostream>

Device::Device(){}

Memo* Device::CreateMemo()
{
    return new Memo(m_state_code);
}

void Device::Recover(Memo *memo)
{
    m_state_code = memo->m_state_code_bak;
}

void Device::Show()
{
    std::cout << m_state_code << std::endl;
}

// memo.h
#ifndef MEMO_H
#define MEMO_H

class Memo
{
public:
    Memo(int state_code);

    int m_state_code_bak;
};

#endif // MEMO_H

// memo.cpp
#include "memo.h"

Memo::Memo(int state_code)
{
    m_state_code_bak = state_code;
}

// caretaker.h
#ifndef CARETAKER_H
#define CARETAKER_H

#include "memo.h"

class Caretaker
{
public:
    Caretaker();
    Memo* m_memo;
};

#endif // CARETAKER_H

// caretaker.cpp
#include "caretaker.h"

Caretaker::Caretaker(){}

客户端:

// main.cpp
#include <iostream>
#include "memo.h"
#include "caretaker.h"
#include "device.h"

using namespace std;

int main(int argc, char *argv[])
{
    Device *dev = new Device();
    dev->m_state_code = 100;
    dev->Show();

    Caretaker *taker = new Caretaker();
    taker->m_memo = dev->CreateMemo();

    dev->m_state_code = 222;
    dev->Show();

    dev->Recover(taker->m_memo);
    dev->Show();

    return 0;
}