Memento Design Pattern

Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later. The intent of the Memento pattern is to provide storage as well as restoration of an object. The mechanism in which you store the object‟s state depends on the required duration of persistence which could be a few seconds, a few days, or possibly years. Storage options include memory (for example Session), a scratch file, or a database.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Soap;

namespace Patterns
{
  
    class MainApp
    {
         
        static void Main()
        {
             // Init sales prospect through object initialization
            SalesProspect s = new SalesProspect
                      {
                         Name = "Joel van Halen",
                          Phone = "(412) 256-0990",
                          Budget = 25000.0
                       };

            // Store internal state
            ProspectMemory m = new ProspectMemory();
            m.Memento = s.SaveMemento();

             // Change originator
            s.Name = "Leo Welch";
            s.Phone = "(310) 209-7111";
            s.Budget = 1000000.0;

             // Restore saved state
            s.RestoreMemento(m.Memento);

            // Wait for user
           Console.ReadKey();
        }
     }

    /// <summary>
    /// The 'Originator' class
    /// </summary>
    [Serializable]
    class SalesProspect
    {
         private string _name;
        private string _phone;
        private double _budget;

        // Gets or sets name
        public string Name
        {
            get { return _name; }
            set
            {
                _name = value;
               Console.WriteLine("Name:   " + _name);
             }
        }

        // Gets or sets phone
        public string Phone
        {
            get { return _phone; }
            set
            {
                _phone = value;
               Console.WriteLine("Phone:  " + _phone);
             }
        }

        // Gets or sets budget
        public double Budget
        {
            get { return _budget; }
            set
            {
                _budget = value;
               Console.WriteLine("Budget: " + _budget);
             }
        }

        // Stores (serializes) memento
        public Memento SaveMemento()
        {
           Console.WriteLine("\nSaving state --\n");

            Memento memento = new Memento();
             return memento.Serialize(this);
        }

         // Restores (deserializes) memento
        public void RestoreMemento(Memento memento)
        {
           Console.WriteLine("\nRestoring state --\n");

            SalesProspect s = (SalesProspect)memento.Deserialize();
            this.Name = s.Name;
            this.Phone = s.Phone;
             this.Budget = s.Budget;
        }
    }

    /// <summary>
    /// The 'Memento' class
    /// </summary>
    class Memento
    {
         private MemoryStream _stream = new MemoryStream();
        private SoapFormatter _formatter = new SoapFormatter();

        public Memento Serialize(object o)
        {
             _formatter.Serialize(_stream, o);
             return this;
        }

         public object Deserialize()
        {
             _stream.Seek(0, SeekOrigin.Begin);
            object o = _formatter.Deserialize(_stream);
             _stream.Close();

             return o;
        }
     }

    /// <summary>
    /// The 'Caretaker' class
    /// </summary>
    class ProspectMemory
    {
         public Memento Memento { get; set; }
    }
}