1.	using System;
2.	using System.Collections.Generic;
3.	 
4.	namespace DoFactory.GangOfFour.Decorator.RealWorld
5.	{
6.	  /// 

7.	  /// MainApp startup class for Real-World 
8.	  /// Decorator Design Pattern.
9.	  /// 
10.	  class MainApp
11.	  {
12.	    /// 

13.	    /// Entry point into console application.
14.	    /// 
15.	    static void Main()
16.	    {
17.	      // Create book
18.	      Book book = new Book("Worley", "Inside ASP.NET", 10);
19.	      book.Display();
20.	 
21.	      // Create video
22.	      Video video = new Video("Spielberg", "Jaws", 23, 92);
23.	      video.Display();
24.	 
25.	      // Make video borrowable, then borrow and display
26.	      Console.WriteLine("\nMaking video borrowable:");
27.	 
28.	      Borrowable borrowvideo = new Borrowable(video);
29.	      borrowvideo.BorrowItem("Customer #1");
30.	      borrowvideo.BorrowItem("Customer #2");
31.	 
32.	      borrowvideo.Display();
33.	 
34.	      // Wait for user
35.	      Console.ReadKey();
36.	    }
37.	  }
38.	 
39.	  /// 

40.	  /// The 'Component' abstract class
41.	  /// 
42.	  abstract class LibraryItem
43.	  {
44.	    private int _numCopies;
45.	 
46.	    // Property
47.	    public int NumCopies
48.	    {
49.	      get { return _numCopies; }
50.	      set { _numCopies = value; }
51.	    }
52.	 
53.	    public abstract void Display();
54.	  }
55.	 
56.	  /// 

57.	  /// The 'ConcreteComponent' class
58.	  /// 
59.	  class Book : LibraryItem
60.	  {
61.	    private string _author;
62.	    private string _title;
63.	 
64.	    // Constructor
65.	    public Book(string author, string title, int numCopies)
66.	    {
67.	      this._author = author;
68.	      this._title = title;
69.	      this.NumCopies = numCopies;
70.	    }
71.	 
72.	    public override void Display()
73.	    {
74.	      Console.WriteLine("\nBook ------ ");
75.	      Console.WriteLine(" Author: {0}", _author);
76.	      Console.WriteLine(" Title: {0}", _title);
77.	      Console.WriteLine(" # Copies: {0}", NumCopies);
78.	    }
79.	  }
80.	 
81.	  /// 

82.	  /// The 'ConcreteComponent' class
83.	  /// 
84.	  class Video : LibraryItem
85.	  {
86.	    private string _director;
87.	    private string _title;
88.	    private int _playTime;
89.	 
90.	    // Constructor
91.	    public Video(string director, string title,
92.	      int numCopies, int playTime)
93.	    {
94.	      this._director = director;
95.	      this._title = title;
96.	      this.NumCopies = numCopies;
97.	      this._playTime = playTime;
98.	    }
99.	 
100.	    public override void Display()
101.	    {
102.	      Console.WriteLine("\nVideo ----- ");
103.	      Console.WriteLine(" Director: {0}", _director);
104.	      Console.WriteLine(" Title: {0}", _title);
105.	      Console.WriteLine(" # Copies: {0}", NumCopies);
106.	      Console.WriteLine(" Playtime: {0}\n", _playTime);
107.	    }
108.	  }
109.	 
110.	  /// 

111.	  /// The 'Decorator' abstract class
112.	  /// 
113.	  abstract class Decorator : LibraryItem
114.	  {
115.	    protected LibraryItem libraryItem;
116.	 
117.	    // Constructor
118.	    public Decorator(LibraryItem libraryItem)
119.	    {
120.	      this.libraryItem = libraryItem;
121.	    }
122.	 
123.	    public override void Display()
124.	    {
125.	      libraryItem.Display();
126.	    }
127.	  }
128.	 
129.	  /// 

130.	  /// The 'ConcreteDecorator' class
131.	  /// 
132.	  class Borrowable : Decorator
133.	  {
134.	    protected List borrowers = new List();
135.	 
136.	    // Constructor
137.	    public Borrowable(LibraryItem libraryItem)
138.	      : base(libraryItem)
139.	    {
140.	    }
141.	 
142.	    public void BorrowItem(string name)
143.	    {
144.	      borrowers.Add(name);
145.	      libraryItem.NumCopies--;
146.	    }
147.	 
148.	    public void ReturnItem(string name)
149.	    {
150.	      borrowers.Remove(name);
151.	      libraryItem.NumCopies++;
152.	    }
153.	 
154.	    public override void Display()
155.	    {
156.	      base.Display();
157.	 
158.	      foreach (string borrower in borrowers)
159.	      {
160.	        Console.WriteLine(" borrower: " + borrower);
161.	      }
162.	    }
163.	  }
164.	}
165.