C + + design mode to recognize Memo mode

Memo Mode (Memento): captures the internal state of an object without compromising encapsulation, and saves the state outside that object. The object can then be restored to its previously saved state.

Pattern implementation:

[Code]struct state{wchar_t wcsstate[260];}; Class Memento{public:memento (state *pstate): M_pstate (pState) {} state *getstate () {return m_pstate;}    Private:friend class originator; State *m_pstate;};        Class Originator{public:originator (): M_pstate (NULL) {} ~originator () {//delete The storage of the state            if (m_pstate) {delete m_pstate;        M_pstate = NULL;    }} void Setmemento (Memento *pmemento);    Memento * Creatememento ();        void SetValue (wchar_t *val) {memset (wcsvalue, 0, 260 * sizeof (wchar_t));    wcscpy_s (Wcsvalue, 260, Val); } void Printstate () {std::wcout << wcsvalue << Std::endl;} private:state *m_pstate; To store the object's state wchar_t wcsvalue[260]; This is the object's real data};    Memento *originator::creatememento () {m_pstate = new State;    if (m_pstate = = null) return null;    Memento *pmemento = new Memento (m_pstate); wcscpy_s (M_pstate->wcsstate, 260, Wcsvalue); Backup the value return pmemento;}    void Originator::setmemento (Memento *pmemento) {m_pstate = Pmemento->getstate ();    Recovery the Data memset (wcsvalue, 0, 260 * sizeof (wchar_t)); wcscpy_s (Wcsvalue, 260, m_pstate->wcsstate);}    Manager the Mementoclass caretaker{public:memento *getmemento () {return m_pmemento;} void Setmemento (Memento *pmemento) {//free The previous Memento if (m_pmemento) {Delete M_pmemento            ;        M_pmemento = NULL;    }//set the new Memento m_pmemento = Pmemento; }private:memento *m_pmemento;};

Client:

[Code]int Main () {     Originator *poriginator = new originator ();    Poriginator->setvalue (L "on");    Poriginator->printstate ();  Output:on    //now I backup the state    caretaker *pcaretaker = new Caretaker ();    Pcaretaker->setmemento (Poriginator->creatememento ());    Set the new state    Poriginator->setvalue (L "off");    Poriginator->printstate (); Output:off//recovery to the old State    Poriginator->setmemento (Pcaretaker->getmemento ());    Poriginator->printstate (); Output:on    if (pcaretaker)        delete pcaretaker;    if (poriginator);        Delete Poriginator;    return 0;}

The above is the C + + design mode of understanding the content of the memo mode, more relevant content please pay attention to topic.alibabacloud.com (www.php.cn)!

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