Rails 3 is going to rock

Yehuda Katz presented the keynote at Rails Underground this morning, and very interesting it was too. The core of his speech revolved around the new version of Rails. Added to the usual tenets of convention over configuration, DRY, etc was a new concept. Opt-in.

Rails 3 has been broken down from a monolithic framework to a set of loosely coupled modules tied together with stupidly simple public interfaces. The router is a module, the renderer is a module, validation is a module, etc, etc. Any can be used or not in your Rails app, or indeed your vanilla Ruby/JRuby/MacRuby app. This direction is beneficial for many reasons:

• New Rails projects can just pull in the parts of the framework they need.
• Existing projects can easily remove dependencies on parts of the framework they don’t need.
• Rails components can be swapped out for alternative implementations

He showed examples of how Sinatra can now effectively be implemented in Rails, how ActiveSupport has been broken up to be more useful outside Rails, and how ActiveModel has replaced ActiveRecord. Very interesting, and very promising. Apparently the APIs will be settled within the next few weeks so edge Rails is going to be stabilising in terms of the interfaces.

One thing is for sure. Rails is going to be a a very different beast.