Implementation Patterns

08 December 2007

A couple of days ago I read Kent Beck's fairly recent book called Implementation Patterns. I especially enjoyed the more philosophical chapters at the beginning. In this part of the book, Beck explains why he thinks it's important that developers should try really hard to write good code.

In terms of books relating to software engineering, I normally prefer slim books over weighty tomes but found this one - which belongs to the former category - by and large a bit too laconic. In fact, one could probably argue that it is not a lot more than merely a very good introduction to programming in Java.

Nevertheless, I had a good time reading it and here are the key points that I'm taking with me:
  • Much more time is spent reading code than writing it.
  • Code that's easy to understand is more maintainable.
  • Try extremely hard to come up with concise and meaningful names for classes, methods and variables.
  • First and foremost, optimise code for readability not performance.
  • Don't restrict yourself to a specific case if you can easily be more generic (e.g. use Collection instead of List if your code doesn't require index-based element access).
  • Don't make members more visible than they absolutely need to.
  • Keep data and logic as close together as possible (i.e. encapsulate).
  • Don't flinch from creating one-line methods if they increase readability (e.g. write void setLoadedFlat(); instead of loaded |= LOADED_BIT;).
  • [Probably my favourite part in the book:] Don't "thoughtlessly obey programming folklore" (e.g. don't always stubbornly use only one return statement if you can use guard statements such as:
    void compute() {
    Client client = getClient();
    if (client == null)
    Request request = client.getRequest();
    if (client.getRequest == null)
  • Implementation strategy is the extraneous information most often included in method names (e.g. use instead of Poll.incrementCounter()).
  • Express as much information as possible through code and structure rather than comments.
Although most of these points seem trivial, I actually catch myself continuously violating one or the other. The book encouraged me question why I'm doing certain things one way and not the other. This, in turn, forces me to either come up with solid reasoning supporting my view or change my habits.