Design Patterns Study Session: Decorator Pattern

Here's an excellent description of the Decorator Pattern:
Usage of wrapper to extend the functionality of a class without modifying the original class.

Introduction : http://www.youtube.com/watch?v=Xk8durvtiys&feature=related
Overview http://www.youtube.com/watch?v=MI_qyfeRk8c&feature=related
Code: http://www.youtube.com/watch?v=HkOdDMePE4Q&feature=related
Executing http://www.youtube.com/watch?v=Ra-33SFHq6M&feature=related