A mere month and a half after the release of Bundler 1.8, we’re happy to announce our next act: Bundler 1.9.

While the CHANGELOG for this version might seem rather short (and light on big new features), there is one cool thing to talk about: Molinillo. Molinillo is a new dependency resolution algorithm developed for CocoaPods – the Cocoa dependency manager. Now, Bundler shares its dependency resolver – one of the most integral parts of a dependency manager – with CocoaPods, with the core logic being independently documented and tested. Molinillo was developed thanks to a generous grant from Stripe for the express purpose of being a generic dependency resolution algorithm that was sharable across different code bases – specifically CocoaPods and Bundler (and possibly even RubyGems)!

Dependencies in Bundler?

Having dependencies inside Bundler itself is a bit crazy: Bundler is a dependency manager for gems, written in Ruby. How could it use gems itself? Well, it can’t really. But we can cheat a bit by shipping Molinillo’s source files inside the bundler gem. This has its own challenge – what if a gem (such as CocoaPods), requires a different version of molinillo (or thor, which is likewise vendored in Bundler)? The solution is to prefix the top-level namespace constant in the vendored gem with Bundler’s own namespace. The upshot of this song-and-dance is that Bundler can share open source libraries just like every other gem!

Updating

To install the last release of Bundler you can run:

$ [sudo] gem install bundler

For all the details, don’t miss the Changelog!