Chapter 2. Selected Design Patterns

Life is like an ever-shifting kaleidoscope—a slight change, and all patterns alter.

— Sharon Salzberg

Design patterns suggest an approach to common problems that arise during software development regardless of programming language. For example, when you need to ensure that your application allows only one instance of a particular class, you need to implement a singleton design pattern. If you need to pass the data between different objects, you create data transfer objects (a.k.a. value objects). There are a number of books written about design patterns and their implementation in different programming languages, including ActionScript 3.0; see ActionScript 3.0 Design Patterns by William Sanders and Chandima Cumaranatunge (O’Reilly). This chapter is not yet another tutorial on patterns. The goal of this chapter is to highlight selected patterns, as you (the developer) may implement them to take advantage of the Flex framework.