Memento

// Memento pattern -- Real World example

using System;

namespace DoFactory.GangOfFour.Memento.RealWorld
{

  // MainApp test application

  class MainApp
  {
    static void Main()
    {
      SalesProspect s = new SalesProspect();
      s.Name = "Noel van Halen";
      s.Phone = "(412) 256-0990";
      s.Budget = 25000.0;

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

      // Continue changing 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.Read();
    }
  }

  // "Originator"

  class SalesProspect
  {
    private string name;
    private string phone;
    private double budget;

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

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

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

    public Memento SaveMemento()
    {
      Console.WriteLine("\nSaving state --\n");
      return new Memento(name, phone, budget);
    }

    public void RestoreMemento(Memento memento)
    {
      Console.WriteLine("\nRestoring state --\n");
      this.Name = memento.Name;
      this.Phone = memento.Phone;
      this.Budget = memento.Budget;
    }
  }

  // "Memento"

  class Memento
  {
    private string name;
    private string phone;
    private double budget;

    // Constructor
    public Memento(string name, string phone, double budget)
    {
      this.name = name;
      this.phone = phone;
      this.budget = budget;
    }

    // Properties
    public string Name
    {
      get{ return name; }
      set{ name = value; }
    }

    public string Phone
    {
      get{ return phone; }
      set{ phone = value; }
    }

    public double Budget
    {
      get{ return budget; }
      set{ budget = value; }
    }
  }

  // "Caretaker"

  class ProspectMemory
  {
    private Memento memento;

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