1.6. Creating a Program

As we just learned, ActionScript programs are made up of classes, which are the blueprints for the interoperating parts (objects) of a program. Typically, the development of a new ActionScript program starts with a design phase, during which the program's functionality is broken into a logical set of classes. Each class is given a name, a set of features, and a role in the larger program. One class in particular is designated as the main class. The main class provides the starting point, or program point of entry, for the application. To start a new program, the Flash runtime automatically creates an instance of the program's main class.

For our virtual zoo example program, we'll name the main class VirtualZoo. As the first step in building the program, we'll create a folder on the filesystem, named virtualzoo. Within that folder, we'll create a subfolder named src (short for source) in which to store all .as files (i.e., all files containing source code).