ActionScript™ 3.0 Bible

Chapter 21. Making Your Application Fault‐Tolerant

Introduction

In this chapter

• Handling errors

• Logging

• Giving feedback to users

You can call it many things: fault‐tolerant, bulletproof, robust. However you describe it, an application that doesn't shatter when things go wrong is a joy to use. These kinds of applications behave well not through luck or coding practices, but because an extensive error handling strategy was devised and applied. This chapter introduces the kinds of errors that can occur and general strategies for handling them.

Developing a Strategy

Why does your application need an error handling strategy? Despite the best efforts of the smartest people, things will always, always, always go wrong. If you do nothing to recover from errors, your program can appear to malfunction to the end user. In Chapter 19, you learned that uncaught exceptions in the release versions of the Flash Player will terminate all code executing on the frame. While this might not sound so bad—at least the program keeps going on the next frame, right?—terminating all code for a frame can be disastrous, skipping vital code and leaving the internals of your program in an invalid state. Imagine if one day, without warning, you were transported forward in time a full year. You would find your taxes have not been paid; you haven't showed up to work; and you haven't answered your spouse's calls. Things would probably not be so great for you. Just like life, most programs have to finish things up in an ...