Bundler allows you to define the gems your application uses, resolve dependencies and load everything up. This is great, because you don’t have to manage all those different gem versions yourself any more.
There is a little problem, though. When you want to use Bundler with Rails 2.3.5. you need to do a bit of extra work. You’ll need to create a file config/preinitializer.rb that contains the following:
require "rubygems" require "bundler" if Gem::Version.