Factory Method

// Factory Method pattern -- Real World example

using System;
using System.Collections;

namespace DoFactory.GangOfFour.Factory.RealWorld
{

  // MainApp test application

  class MainApp
  {
    static void Main()
    {
      // Note: constructors call Factory Method
      Document[] documents = new Document[2];
      documents[0] = new Resume();
      documents[1] = new Report();

      // Display document pages
      foreach (Document document in documents)
      {
        Console.WriteLine("\n" + document.GetType().Name+ "--");
        foreach (Page page in document.Pages)
        {
          Console.WriteLine(" " + page.GetType().Name);
        }
      }

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

  // "Product"

  abstract class Page
  {
  }

  // "ConcreteProduct"

  class SkillsPage : Page
  {
  }

  // "ConcreteProduct"

  class EducationPage : Page
  {
  }

  // "ConcreteProduct"

  class ExperiencePage : Page
  {
  }

  // "ConcreteProduct"

  class IntroductionPage : Page
  {
  }

  // "ConcreteProduct"

  class ResultsPage : Page
  {
  }

  // "ConcreteProduct"

  class ConclusionPage : Page
  {
  }

  // "ConcreteProduct"

  class SummaryPage : Page
  {
  }

  // "ConcreteProduct"

  class BibliographyPage : Page
  {
  }

  // "Creator"

  abstract class Document
  {
    private ArrayList pages = new ArrayList();

    // Constructor calls abstract Factory method
    public Document()
    {
      this.CreatePages();
    }

    public ArrayList Pages
    {
      get{ return pages; }
    }

    // Factory Method
    public abstract void CreatePages();
  }

  // "ConcreteCreator"

  class Resume : Document
  {
    // Factory Method implementation
    public override void CreatePages()
    {
      Pages.Add(new SkillsPage());
      Pages.Add(new EducationPage());
      Pages.Add(new ExperiencePage());
    }
  }

  // "ConcreteCreator"

  class Report : Document
  {
    // Factory Method implementation
    public override void CreatePages()
    {
      Pages.Add(new IntroductionPage());
      Pages.Add(new ResultsPage());
      Pages.Add(new ConclusionPage());
      Pages.Add(new SummaryPage());
      Pages.Add(new BibliographyPage());
    }
  }
}