Description:

When DHH first announced Rails 3, he was very careful to say that we would not be rewriting the framework from scratch. There was a lot already there, and while we would make quite a few changes before the final release, including incremental rewrites of some parts of Rails, we never considered a full-on rewrite. In order to get to the final release, we adhered carefully to a few rules. (1) do big refactors on master, not a branch; (2) keep the old tests passing, and be very careful about large test changes; (3) don't break backward compatibility with any public-facing API; and (4) keep the Depot tests passing. In this talk, Yehuda will cover what techniques the Rails team used to maintain a very high level of backward compatibility with Rails 2.3, even while mostly rewriting parts of Rails, like the core of ActionController and almost all of Railties.