Flyweight

// Flyweight pattern -- Real World example

using System; using System.Collections; namespace DoFactory.GangOfFour.Flyweight.RealWorld {    // MainApp test application    class MainApp   {      static void Main()     {        // Build a document with text        string document = "AAZZBBZB";        char[] chars = document.ToCharArray();       CharacterFactory f = new CharacterFactory();        // extrinsic state        int pointSize = 10;        // For each character use a flyweight object        foreach ( char c in chars)       {         pointSize++;         Character character = f.GetCharacter(c);         character.Display(pointSize);       }        // Wait for user       Console.Read();     }   }    // "FlyweightFactory"    class CharacterFactory   {      private Hashtable characters = new Hashtable();      public Character GetCharacter( char key)     {        // Uses "lazy initialization"       Character character = characters[key] as Character;        if (character == null)       {          switch (key)         {            case 'A': character = new CharacterA(); break;            case 'B': character = new CharacterB(); break;              //...            case 'Z': character = new CharacterZ(); break;         }         characters.Add(key, character);       }        return character;     }   }    // "Flyweight"    abstract class Character   {      protected char symbol;      protected int width;      protected int height;      protected int ascent;      protected int descent;      protected int pointSize;      public abstract void Display( int pointSize);   }    // "ConcreteFlyweight"    class CharacterA : Character   {      // Constructor      public CharacterA()     {        this.symbol = 'A';        this.height = 100;        this.width = 120;        this.ascent = 70;        this.descent = 0;     }      public override void Display( int pointSize)     {        this.pointSize = pointSize;       Console.WriteLine( this.symbol +         " (pointsize " + this.pointSize + ")");     }   }    // "ConcreteFlyweight"    class CharacterB : Character   {      // Constructor      public CharacterB()     {        this.symbol = 'B';        this.height = 100;        this.width = 140;        this.ascent = 72;        this.descent = 0;     }      public override void Display( int pointSize)     {        this.pointSize = pointSize;       Console.WriteLine( this.symbol +         " (pointsize " + this.pointSize + ")");     }   }    // ... C, D, E, etc.    // "ConcreteFlyweight"    class CharacterZ : Character   {      // Constructor      public CharacterZ()     {        this.symbol = 'Z';        this.height = 100;        this.width = 100;        this.ascent = 68;        this.descent = 0;     }      public override void Display( int pointSize)     {        this.pointSize = pointSize;       Console.WriteLine( this.symbol +         " (pointsize " + this.pointSize + ")");     }   } }