You’ll typically find it fairly straightforward to choose which version of ActionScript to use when you start a new project. You usually decide based on which version of the Flash Player you’re trying to target, the need for enhanced performance, or a specific feature you wish to use. Deciding what to do with existing projects, however, is another matter. Often you need to determine whether or not it’s worth the time and effort to migrate to ActionScript 3.0 from a prior version of the language, or just to start over.
You can’t easily determine what to do; each project’s characteristics probably significantly affect your decision. The clarity of your existing code, the extent to which you use particular features, project size, and your comfort level, among other factors, help you decide.
This chapter walks you through a small-scale, manufactured example of a migration from ActionScript 2.0 to ActionScript 3.0. Read the text linearly, as code isn’t always explained in detail twice. It is very important to understand that this example isn’t a demonstration of real-world best practices at work. This example is significantly constrained, and attempts to insert as many migration issues as possible into its tiny footprint. Throughout the example, what may appear to be odd choices, poorly optimized code, or even mistakes, have been intentionally injected into the code to either set up a migration task or bring the two versions into a parallel structure.