Two Fantastic Uses for AspectJ: Part One, Backward Compatibility

NOTE: I’m cross-posting this article on both my Build Chimp and Sonatype blogs. Recently, I’ve been spending a lot of time hacking on Maven trunk (what will become Maven 2.1 eventually), and trying to tackle some of the larger problems with plugin- and extension-loading, and planning out the order of mojo execution for a given build ahead of time. While we’ve had to some really encouraging success in addressing these sorts of broad problems (along with artifact resolution, which Jason van Zyl has been paying a lot of attention to), we’ve run into other, stickier problems relating to backward compatibility. You see, some of the more advanced Maven plugins out there make use of some pretty deeply buried Maven components to do their jobs. This means that changing the APIs of some of these deep components will break those plugins, resulting in NoSuchMethodErrors. Part of the root problem here is allowing plugins to lookup any old component in the system that they want to; another part is ...