Structural Patterns - Flyweight

Flyweight.cs

using System;
using System.Collections;

class MainApp
{
    static void Main()
    {
        // Arbitrary extrinsic state 
        int extrinsicstate = 22;

        FlyweightFactory f = new FlyweightFactory();

        // Work with different flyweight instances 
        Flyweight fx = f.GetFlyweight("X");
        fx.Operation(--extrinsicstate);

        Flyweight fy = f.GetFlyweight("Y");
        fy.Operation(--extrinsicstate);

        Flyweight fz = f.GetFlyweight("Z");
        fz.Operation(--extrinsicstate);

        UnsharedConcreteFlyweight uf = new
          UnsharedConcreteFlyweight();

        uf.Operation(--extrinsicstate);

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

// "FlyweightFactory" 
class FlyweightFactory
{
    private Hashtable flyweights = new Hashtable();

    // Constructor 
    public FlyweightFactory()
    {
        flyweights.Add("X", new ConcreteFlyweight());
        flyweights.Add("Y", new ConcreteFlyweight());
        flyweights.Add("Z", new ConcreteFlyweight());
    }

    public Flyweight GetFlyweight(string key)
    {
        return ((Flyweight)flyweights[key]);
    }
}

// "Flyweight" 
abstract class Flyweight
{
    public abstract void Operation(int extrinsicstate);
}

// "ConcreteFlyweight" 

class ConcreteFlyweight : Flyweight
{
    public override void Operation(int extrinsicstate)
    {
        Console.WriteLine("ConcreteFlyweight: " + extrinsicstate);
    }
}

// "UnsharedConcreteFlyweight" 
class UnsharedConcreteFlyweight : Flyweight
{
    public override void Operation(int extrinsicstate)
    {
        Console.WriteLine("UnsharedConcreteFlyweight: " +
          extrinsicstate);
    }
}