ActionScript: The Definitive Guide

Chapter 12. Objects and Classes

This chapter covers so-called object-oriented programming (OOP), which is new territory for many readers. We’ll cover some of the terminology and show some applied examples to make it all concrete. You may have heard that OOP is some big mystery or that it’s difficult to understand. Quite the contrary, the concepts are highly intuitive and the OOP process much easier than you may have been led to believe. At its heart, OOP simply means that you treat portions of your program as self-contained objects. This is easy to grasp once you realize that everything you deal with in the real world is a self-contained object. Your dog, your parents, your car, and your computer are all self-contained objects meaning that they do some things independently and do other things at your request even if you don’t know the inner details of how they work.

You don’t have to be a biologist to get your dog to fetch a stick; you don’t need to be a mechanical engineer to drive your car; you don’t need to be a psychoanalyst to interact with your parents; and rumors to the contrary, you don’t need to be a computer scientist to check your email. All you need to know is the commands an object is willing to obey (which are called methods ) and the results those commands produce. For example, if you press the gas pedal of your car, you can expect it to accelerate. If you tell your dog to sit, you can expect him to sit. Armed with this commonsense context of what an object is in the ...