Design Patterns 18 - 备忘录模式

class Originator {
    private string state;
    public string State {
        get {
            return state;
        }
        set {
            state = value;
        }
    }

    public Memento CreateMemento {
        return (new Memento(state));
    }

    public void SetMemento(Memento memento) {
        state = memento.State;
    }

    public void Show() {
        // todo
    }
}

class Memento {
    private string state;

    public Memento(string state) {
        this.state = state;
    }

    public string State {
        get {
            return state;
        }
    }
}

class Caretaker {
    private Memento memento;

    public Memento Memento {
        get {
            return memento;
        }
        set {
            memento = value;
        }
    }
}

public static void Main(string[] args) {
    Originator originator = new Originator();
    originator.State = "On";
    originator.Show();

    Caretaker caretaker = new Caretaker();
    caretaker.Memento = originator.CreateMemento();

    originator.State = "Off";
    originator.Show();

    originator.SetMemento(caretaker.Memento);
    originator.Show();
}