Memento Pattern

  • Behavioral pattern
  • The intent of this pattern is to capture and externalize and objects internal state so that the object can be restored to this state later, without violating encapsulation.
				
					using Newtonsoft.Json;

namespace memento
{
    //Originator 
    class Chess 
    {
        public string? Move;

        public Memento CreateState()
        {
            return new Memento(Move!);
        }

        public void Undo(Memento memento)
        {
            Move = memento.Move;
        }

    }

    //Memento
    public class Memento
    {
        public string Move { get { return move; } }

        private string ? move;

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

    }

    //Creator
    class ChessManager
    {
        Stack<Memento> mementos = new Stack<Memento>();

        public void AddMememento(Memento state)
        {
            mementos.Push(state);
        }

        public Memento GetMemento()
        {
            return mementos.Pop();
        }
    }
}

				
			
				
					// See https://aka.ms/new-console-template for more information



using memento;


var chess = new Chess() { Move = "Horse Moves L step"};
var chessManager = new ChessManager();
chessManager.AddMememento(chess.CreateState());
Console.WriteLine(chess.Move);

chess.Move = "soldier moves 1 step";
chessManager.AddMememento(chess.CreateState());
Console.WriteLine(chess.Move);

chess.Move = "Queen moves";
chessManager.AddMememento(chess.CreateState());
Console.WriteLine(chess.Move);

Console.WriteLine("-------------------------");
chess.Undo(chessManager.GetMemento());
chess.Undo(chessManager.GetMemento());
Console.WriteLine(chess.Move);

chess.Undo(chessManager.GetMemento());
Console.WriteLine(chess.Move);

Horse Moves L step
soldier moves 1 step
Queen moves
————————-
soldier moves 1 step
Horse Moves L step

https://github.com/AnuragDaCoder/memento

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