I like Rails's
config.gem feature: it's simple and gives you a lot of functionality for cheap, much like Rails itself. I just spent half a day tracking down a problem because we were overusing it.
I tend to be fanatical about minimizing dependencies as it has bit me several times in the past. In this case, we were using
config.gem to load a test dependency, redgreen. All that gem does is colorize your test output. There's no reason to list it as an application dependency but the team wanted all gems to install with
rake gems:install. It didn't sit right with me at the time but I didn't feel strongly enough to raise the issue. Well as it turns out when you add redgreen via
config.gem, it adds a test/unit
at_exit handler that exhibits some odd behavior, including breaking the test suite on our sandbox/ci server.
I'm not blaming redgreen and I'm not blaming
config.gem since we really weren't using either as designed. Once it was loaded as normal, everything worked as expected. Lesson reinforced: keep your app's dependencies as simple as possible. There's no reason why redgreen should be installed on our production servers.