Prototype Design Pattern

// Prototype pattern -- Structural example

using System;

namespace DoFactory.GangOfFour.Prototype.Structural
{
  
  // MainApp test application

  class MainApp
  {
    
    static void Main()
    {
      // Create two instances and clone each

      ConcretePrototype1 p1 = new ConcretePrototype1("I");
      ConcretePrototype1 c1 = (ConcretePrototype1)p1.Clone();
      Console.WriteLine ("Cloned: {0}", c1.Id);

      ConcretePrototype2 p2 = new ConcretePrototype2("II");
      ConcretePrototype2 c2 = (ConcretePrototype2)p2.Clone();
      Console.WriteLine ("Cloned: {0}", c2.Id);

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

  // "Prototype"

  abstract class Prototype
  {
    private string id;

    // Constructor
    public Prototype(string id)
    {
      this.id = id;
    }

    // Property
    public string Id
    {
      get{ return id; }
    }

    public abstract Prototype Clone();
  }

  // "ConcretePrototype1"

  class ConcretePrototype1 : Prototype
  {
    // Constructor
    public ConcretePrototype1(string id) : base(id)
    {
    }

    public override Prototype Clone()
    {
      // Shallow copy
      return (Prototype)this.MemberwiseClone();
    }
  }

  // "ConcretePrototype2"

  class ConcretePrototype2 : Prototype
  {
    // Constructor
    public ConcretePrototype2(string id) : base(id)
    {
    }

    public override Prototype Clone()
    {
      // Shallow copy
      return (Prototype)this.MemberwiseClone();
    }
  }
}

using System;
using System.Collections;

namespace DoFactory.GangOfFour.Prototype.RealWorld
{
  
  // MainApp test application

  class MainApp
  {
    static void Main()
    {
      ColorManager colormanager = new ColorManager();

      // Initialize with standard colors
      colormanager["red" ] = new Color(255, 0, 0);
      colormanager["green"] = new Color( 0, 255, 0);
      colormanager["blue" ] = new Color( 0, 0, 255);

      // User adds personalized colors
      colormanager["angry"] = new Color(255, 54, 0);
      colormanager["peace"] = new Color(128, 211, 128);
      colormanager["flame"] = new Color(211, 34, 20);

      Color color;

      // User uses selected colors
      string name = "red";
      color = colormanager[name].Clone() as Color;

      name = "peace";
      color = colormanager[name].Clone() as Color;

      name = "flame";
      color = colormanager[name].Clone() as Color;

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

  // "Prototype"

  abstract class ColorPrototype
  {
    public abstract ColorPrototype Clone();
  }

  // "ConcretePrototype"

  class Color : ColorPrototype
  {
    private int red;
    private int green;
    private int blue;

    // Constructor
    public Color(int red, int green, int blue)
    {
      this.red = red;
      this.green = green;
      this.blue = blue;
    }

    // Create a shallow copy
    public override ColorPrototype Clone()
    {
      Console.WriteLine(
        "Cloning color RGB: {0,3},{1,3},{2,3}",
        red, green, blue);

      return this.MemberwiseClone() as ColorPrototype;
    }
  }

  // Prototype manager

  class ColorManager
  {
    Hashtable colors = new Hashtable();

    // Indexer
    public ColorPrototype this[string name]
    {
      get
      {
        return colors[name] as ColorPrototype;
      }
      set
      {
        colors.Add(name, value);
      }
    }
  }
}

// Prototype pattern -- .NET optimized

Two editions: C# and VB.NET

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