using System;

     // These two classes could be part of a framework,

     // which we will call DP

     // ===============================================

     class Director

     {

         public void Construct(AbstractBuilder abstractBuilder)

         {

             abstractBuilder.BuildPartA();

             if (== ) //represents some local decision inside director

             {

                 abstractBuilder.BuildPartB();

             }

             abstractBuilder.BuildPartC();

         }

     }

     abstract class AbstractBuilder

     {

         abstract public void BuildPartA();

         abstract public void BuildPartB();

         abstract public void BuildPartC();

     }

     // These two classes could be part of an application

     // =================================================

     class ConcreteBuilder : AbstractBuilder

     {

         override public void BuildPartA()

         {

             // Create some object here known to ConcreteBuilder

             Console.WriteLine("ConcreteBuilder.BuildPartA called");

         }

         override public void BuildPartB()

         {

             // Create some object here known to ConcreteBuilder

             Console.WriteLine("ConcreteBuilder.BuildPartB called");

         }

         override public void BuildPartC()

         {

             // Create some object here known to ConcreteBuilder

             Console.WriteLine("ConcreteBuilder.BuildPartC called");

         }

     }    

     /// <summary>

     ///    Summary description for Client.

     /// </summary>

     public class Client

     {

         public static int Main(string[] args)

         {

             ConcreteBuilder concreteBuilder = new ConcreteBuilder();

             Director director = new Director();

             director.Construct(concreteBuilder);

             return ;

         }

     }