Inheritance is evil, and must be destroyed: part 1
Written by on October 11th, 2007 in Ajax News.
When we wrote about Bernard Sumption’s Animator.js there was a lot of “interest” in Bernies position that OO inheritance sucks.
Bernie decided to fuel the fire and expanded his thoughts, explaining how the strategy pattern is in fact your saviour 
All of the pain caused by inheritance can be traced back to the fact that inheritance forces ‘is-a’ rather than ‘has-a’ relationships. If class R2Unit extends Droid, then a R2Unit is-a Droid. If class Jedi contains an instance variable of type Lightsabre, then a Jedi has-a Lightsabre.
The difference between is-a and has-a relationships is well known and a fundamental part of OOAD, but what is less well known is that almost every is-a relationship would be better off re-articulated as a has-a relationship.
The article takes the world of Jedi and then writes a real example using Balls and BouncingBalls. He also explains why he thinks that Flash’s DisplayObject hierarchy is good, and that EventDispatcher is bad.
Source: Ajaxian
Original Article: http://feeds.feedburner.com/~r/ajaxian/~3/168480183/inheritance-is-evil-and-must-be-destroyed-part-1