Flyweight in C#
Why read if you can watch?
Watch Flyweight's video tutorialUses sharing to support large numbers of fine-grained objects efficiently.
This structural code demonstrates the Flyweight pattern in which a relatively small number of objects is shared many times by different clients.
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);
}
}
ConcreteFlyweight: 21
ConcreteFlyweight: 20
ConcreteFlyweight: 19
UnsharedConcreteFlyweight: 18
