You know, there are these two guys working in broad daylight on Bundler, Yehuda and Carl (he’s the one in the sidecar), but I don’t think people have really grasped the importance of what they are doing.

Bundler is just as mind blowing a development for Rails 3 as any other change in the Rails framework. As the wycats states; “Bundler manages an application’s dependencies through it’s entire life across many machines systematically and repeatably”.

To me, bundler takes the guess work out of dependency management, it simply provides you with a way to know what gems you are distributing with your application, we (as a Ruby community) have never had such a comprehensive solution to gem management before.

But like any new tool, it is going to go through some growing pains. To my surprise, (and the credit of the authors) the growing pains have been short and sharp, rapidly fixed as bundler grows to whole new levels of reliability.

And also like any new tool, it is optimised for certain environments, in bundler’s case, USE RVM! If you are not using RVM and you are running multiple rubies with Bundler, honestly, you’re mad. Do yourself a favour, download RVM and use it. You can then specify sand boxes of gem sets for each ruby or application you have, goodbye incompatible gems conflicting with each other.

To give you a taste of just how awesome the Bundle RVM marriage is, check this out:

After you install RVM, go into the directory of each app you want to have their own private gem sets and create a file called .rvmrc and put in there:

rvm ruby-1.8.7@railsplugins

Which is what I have on my RailsPlugins.org repository.

Then change into the directory, and RVM will tell you it doesn’t know about the gemset:

$ cd railsplugins Gemset 'railsplugins' does not exist, rvm gemset create 'railsplugins' first.

OK, so go ahead and create the gemset and have a look at what gems you have installed:

$ rvm gemset create 'railsplugins' Gemset 'railsplugins' created. $ gem list *** LOCAL GEMS *** $ ruby -v ruby 1.8.7 (2010-01-10 patchlevel 249) [i686-darwin10.2.0]

Good… see? A clean ruby 1.8.7, as if you just bought the computer.

Now go ahead and install bundler for this clean gemset:

$ gem install --no-rdoc --no-ri bundler Successfully installed bundler-0.9.14 1 gem installed

Cool, now all that we have left is to give bundler the reins and tell it to do what it does best:

$ bundle install <lots of output>

Now when you gem list for that directory you will get all the gems in your gem file, and when you move to a different directory (with a different .rvmrc) all your gems get magically switched out for the new set.

Honestly, with the number of different clients I am coding for and the number of libraries I am working on, I can’t imagine being any where near as productive without the RVM and bundler team.

Yehuda has made a fairly comprehensive guide to bundler at the Gem Bundler site which you should read through and understand, and I have only brushed the surface of RVM, you should check it out as well at the RVM site

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