This chapter covers the Decorator pattern.
GoF Definition
Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
Concept
This pattern promotes the concept that your class should be closed for modification but open for extension. In other words, you can add a functionality without disturbing the existing functionalities. The concept is useful when you want to add some special functionality to a specific object instead of the whole class. This pattern prefers object composition over inheritance. ...
