RVM.el and Inf-Ruby (Emacs Reboot #14)

With my Emacs config files better organized, it’s time now to turn my attention to improving my experience editing Ruby files. First of all, I want to be able to quickly and easily drop into an IRB session from the code I’m working on.

First, I grab the rvm.el package from GitHub. This package is also available via ELPA, but the version in the archives is a little older and doesn’t work as well. I want the latest.

git submodule add https://github.com/senny/rvm.el.git elisp/external/rvm.el

I open up the rvm.el file, and byte-compile it with M-x byte-compile-file. Then I generate autoloads for it with M-x update-file-autoloads. I tell emacs to save the generated autoloads file as ~/.emacs24.d/init.d/rvm-loaddefs.el, so it will be picked up by my init-loading loop.

I integrate RVM into my Ruby editing experience by adding a new hook to ruby-mode-hook:

(add-hook 'ruby-mode-hook
          (lambda () (rvm-activate-corresponding-ruby)))

Now whenever I open a Ruby file, Emacs looks for the corresponding .rvmrc (if any) and reconfigures the environment to ensure that the appropriate Ruby executable will be used.

That done, I alter my “required packages” list to include the inf-ruby package, and then re-evaluate the code which installs the package list. Inf-Ruby stands for “Inferior Ruby”; it is a package which makes it possible to run an IRB session inside an Emacs buffer.

(setq abg-required-packages 
      (list 'xml-rpc 'magit 'gh 'inf-ruby))
; ...
(dolist (package abg-required-packages)
  (when (not (package-installed-p package))
    (package-install package)))

Now when I edit a Ruby file, at any time I can hit C-x C-s to drop into an IRB buffer and evaluate live Ruby code. rvm.el ensures that it is the correct Ruby version and gemset for the current project. inf-ruby has lots of handy keybindings for evaluating bits of Ruby files within the IRB buffer, so it’s easy to make a change to the code, send the new code to the inf-ruby buffer, and then play with the updated code without restarting the IRB session.

[boilerplate bypath=”emacs-reboot”]


  1. Nice article. I’ve switched to MacVim for most of my programming work, but I miss emacs. However, I do like Vi’s keybinding better. Do you use Viper-mode?

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