Savior of the day
Jesse was born and raised in Australia, and now lives in London. He is one of the original founders of http://ActionScript.org, and was formerly a Flash developer, teacher, author and speaker. While Jesse no longer works as a full-time Flash professional, he still enjoys actively participating in the http://ActionScript.org community as time permits.
Reading even the first chapter of AA3WDP is probably a good start. It whirls through the concepts of UML, Use Cases, CRC Cards, Encapsulation, Inheritance and Composition, and a variety of other Object Orientation principles. It gives good high level guidance to those who might already know how to write OO ActionScript but struggle with when and where to apply Object Orientation, and how to architect their applications.
Note the use of the terms "concepts" and "high level" above. None of the descriptions in this book will make you an expert in the relevant concepts. They will however make you aware of ways and means of approaching your work which people all over the world use for good reason. For those elements relevant to you, you can conduct your own further research to learn more, and hopefully achieve better results, which is what Best Practices are all about. (Importantly, in this review I'm not talking about best practices such as keeping all your code in a layer called 'ActionScript'. I'm talking about the software architecture of your Flash application; how you design the pieces, and how well they fit together.)
AA3WDP brings with it just enough information to entice the advanced ActionScript professional into the world of Best Practices only so far as they need to go to meet their ends. It gives you a taste of the virtues and downfalls of Design Patterns (in particular, but Best Practices more generally), without forcing you to read volumes.
Because this book is aimed at advanced ActionScript professionals, there is no fussing about with introductions to basic ActionScript concepts. Explanations of code are concise and assume you can read the code yourself, and get an idea of what it's doing. Things are explained once, and explained well. I must admit that many of these topics weren't new to me so I intentionally sought out those that were and read them fully. I found that they provided me with enough information to understand the concepts being discussed, and apply them at a high level. If I needed / wanted more detail, I would have to go elsewhere (e.g. online, or one of those tomes I had to buy at University *shudder*).
AA3WDP provides enough detail to leave you with a good understanding
the concepts being put forward, and keep them in the back of your mind for when
you may wish to apply them. It also provides enough of a practical example to
get how the pieces fit together. If you still need more, there are volumes of
free information online, and some great books written on each of the topics covered,
to provide the added detail you may be seeking. Importantly, this book shows how to implement these concepts in object oriented, ActionScript 3 code, which is often the hardest part when it comes to following design patterns.
Advanced ActionScripters will find themselves recognizing concepts discussed in this book and realizing that the project they did yesterday, or last month applied that concept to an extent. In fact, the book itself doesn't go into too much depth about when you would use a certain best practice, or design pattern, but if you're a weathered ActionScripter, you'll probably recognize those automatically. You will also likely find that best practice approach may have provided you with a more elegant way of achieving the same result, or something which you could have more readily reused later on.
Ultimately this is a very good resource to have at your disposal. There are a few quirks; e.g. use of certain UML diagrams whose syntax is not explained (that I saw) in the book, and thus might not make sense to a casual reader, but I only point that out because I was looking for something bad to say.If developing reasonable sized ActionScript applications (in Flex or Flash of any flavor) is a significant part of your day to day life, and you don't already know much about design patterns and general software engineering best practices, convince the boss (or spouse) that this is a worthwhile expense. It is.