Abstract Factory

// Abstract Factory pattern -- Real World example

using System; namespace DoFactory.GangOfFour.Abstract.RealWorld {    // MainApp test application    class MainApp   {      public static void Main()     {        // Create and run the Africa animal world       ContinentFactory africa = new AfricaFactory();       AnimalWorld world = new AnimalWorld(africa);       world.RunFoodChain();        // Create and run the America animal world       ContinentFactory america = new AmericaFactory();       world = new AnimalWorld(america);       world.RunFoodChain();        // Wait for user input       Console.Read();     }   }    // "AbstractFactory"    abstract class ContinentFactory   {      public abstract Herbivore CreateHerbivore();      public abstract Carnivore CreateCarnivore();   }    // "ConcreteFactory1"    class AfricaFactory : ContinentFactory   {      public override Herbivore CreateHerbivore()     {        return new Wildebeest();     }      public override Carnivore CreateCarnivore()     {        return new Lion();     }   }    // "ConcreteFactory2"    class AmericaFactory : ContinentFactory   {      public override Herbivore CreateHerbivore()     {        return new Bison();     }      public override Carnivore CreateCarnivore()     {        return new Wolf();     }   }    // "AbstractProductA"    abstract class Herbivore   {   }    // "AbstractProductB"    abstract class Carnivore   {      public abstract void Eat(Herbivore h);   }    // "ProductA1"    class Wildebeest : Herbivore   {   }    // "ProductB1"    class Lion : Carnivore   {      public override void Eat(Herbivore h)     {        // Eat Wildebeest       Console.WriteLine( this.GetType().Name +         " eats " + h.GetType().Name);     }   }    // "ProductA2"    class Bison : Herbivore   {   }    // "ProductB2"    class Wolf : Carnivore   {      public override void Eat(Herbivore h)     {        // Eat Bison       Console.WriteLine( this.GetType().Name +         " eats " + h.GetType().Name);     }   }    // "Client"    class AnimalWorld   {      private Herbivore herbivore;      private Carnivore carnivore;      // Constructor      public AnimalWorld(ContinentFactory factory)     {       carnivore = factory.CreateCarnivore();       herbivore = factory.CreateHerbivore();     }      public void RunFoodChain()     {       carnivore.Eat(herbivore);     }   } }