Looks pretty cool but one thing I am missing is the "russian doll
pattern" Yehuda and Carl mentioned at RailsConf 09. I know the talk
wasn't based on any existing code, but I assumed the mountable apps
topic will be a key feature in Rails 3.
Reading the docs and the code, there doesn't seem to be anything
mountable apps-related like a namespace feature (config.app_namespace)
in the current release.
Now my question: What's the state of the whole mountable app thing? Is
it already in and I just looked in the wrong place, is this going to
be a 3.x feature or did you guys cross it off the list?
In Rails 3.0, the Engine class is the superclass of Application. We got pretty far along, but there are some kinks that need to be worked out in 3.x before the ideas Carl and I outlined are seamless.
What you stumbled across is pretty much all in the lifo/docrails repository now.
Watch out for more guides, we will be doing a series of write ups
covering all aspects of this area. The full intention is to make an
even more thriving and co-ordinated plugin developer community around
rails.
While the kinks aren't out on the general pluggable app, you can mount
any rack related app already (check out my blog for a simple writeup
on this) which means you COULD distribute right now a gem that plugs
into rails, inserts it routes and just works after the user adds your
gem to their Gemfile.