New article from the ActionScript Technology Center by Peter Elst about Object-oriented programming with AS3. I know a lot of Flasher only used some procedural programming but now the AS3 change it all. You really need to understand well OOP to have the most of Flash CS3 and Flex.
The concept of classes is at the heart of all object-oriented code development. If you’re not already familiar with object-oriented programming (OOP), this article will get you started writing ActionScript 3.0 classes. Writing classes has never been easier than with ActionScript 3.0. Whether you are new to ActionScript altogether or are new to working with ActionScript 3.0, you’ll find that writing classes allows you to create projects that are easier to manage and maintain.