Question

I need to get the current working directory of a gem from within a Rails application.

I currently use

`bundle show foo`.strip

This works great in my environment, but:

• it’s slow because it requires loading a shell
• it will probably break when somebody tries to run the app on Windows or on JRuby or when their $PATH points at a different ruby than the one used to start the app

So I’d like a way to do this without invoking a subshell.

The RDOC for Bundler hasn’t been helpful. You used to be able to get this sort of information from Rails itself in Rails 2, but it appears that Rails 3 lets Bundler handle it.

Answer 1

If a gem is in your Gemfile/Gemfile.lock, its path appears in the $LOAD_PATH global variable. You can take advantage of this fact:

$:.grep(/activerecord/).first

$: is the same as $LOAD_PATH. You can use either.

Another approach:

Bundler.load.specs.find{|s| s.name == 'activerecord' }.try(:full_gem_path)