inf-ruby provides a REPL buffer connected to a Ruby subprocess.

package.el is the built-in package manager in Emacs 24+. On Emacs 23 you will need to get package.el yourself if you wish to use it.

inf-ruby is available on both major package.el community maintained repos: Marmalade and MELPA.

If you're not already using one of them, follow their installation instructions: Marmalade, MELPA.

And then you can install inf-ruby with the following command:

M-x package-install [RET] inf-ruby [RET]

or by adding this bit of Emacs Lisp code to your Emacs initialization file (.emacs or init.el):

(unless (package-installed-p 'inf-ruby)
  (package-install 'inf-ruby))

If the installation doesn't work try refreshing the package list:

M-x package-refresh-contents [RET]

el-get is another popular package manager for Emacs. If you're an el-get user just do M-x el-get-install.

If you're installing manually, you'll need to:

• drop the inf-ruby.el file somewhere on your load path (perhaps ~/.emacs.d/vendor)
• Add the following lines to your .emacs (or init.el) file:

(autoload 'inf-ruby-minor-mode "inf-ruby" "Run an inferior Ruby process" t)
(add-hook 'ruby-mode-hook 'inf-ruby-minor-mode)

Or, for enh-ruby-mode:

(add-hook 'enh-ruby-mode-hook 'inf-ruby-minor-mode)

Installation via package.el interface does the above for you automatically.

Additionally, consider adding

(add-hook 'compilation-filter-hook 'inf-ruby-auto-enter)

or

(add-hook 'compilation-filter-hook 'inf-ruby-auto-enter-and-focus)

to your init file to automatically switch from common Ruby compilation modes to interact with a debugger. The latter snippet will also select the compilation window and move point to the breakpoint prompt.

If you wish to add other interpreter prompt patterns, see the description in the wiki.

inf-ruby comes bundled in Emacs Prelude. If you're a Prelude user you can start using it right away.

A simple IRB process can be fired up with M-x inf-ruby.

To launch a REPL with project-specific console instead, type M-x inf-ruby-console-auto. It recognizes several project types, including Rails, gems and anything with racksh in their Gemfile.

To run the project specific console in a Docker (or Podman or other) container, or in another shell or host, set inf-mode-wrapper-command which will be passed to format to produce the command for launching the console, so it must include %s. For instance, one can add the following to a .dir-locals.el file at the root of a project:

((ruby-mode . ((inf-ruby-wrapper-command . "docker exec -i container_name %s"))))

When entered, this mode runs comint-mode-hook and inf-ruby-mode-hook (in that order).

• ruby-switch-to-inf switches the current buffer to the ruby process buffer.
• ruby-send-definition sends the current definition to the ruby process.
• ruby-send-region sends the current region to the ruby process.
• ruby-send-definition-and-go and ruby-send-region-and-go switch to the ruby process buffer after sending their text.

• RET after the end of the process' output sends the text from the end of process to point.
• RET before the end of the process' output copies the sexp ending at point to the end of the process' output, and sends it.
• DEL converts tabs to spaces as it moves back.
• TAB completes the input at point. IRB, Pry and Bond completion is supported.
• C-M-q does TAB on each line starting within following expression.
• Paragraphs are separated only by blank lines. # start comments.
• If you accidentally suspend your process, use comint-continue-subjob to continue it.

To see the list of the keybindings defined by inf-ruby-minor-mode, type M-x describe-function [RET] inf-ruby-minor-mode [RET].

• To use Pry in inf-ruby with Ruby 3.3, you should install readline-ext (and add it to Gemfile, if it is used) (dgutov/robe#147).

• If there is a triangle instead of prompt, or you see a reline related error, or your REPL simply doesn't react to input, try putting the following in your ~/.irbrc:

IRB.conf[:USE_MULTILINE] = false if ENV['INSIDE_EMACS']
IRB.conf[:USE_READLINE] = false if ENV['INSIDE_EMACS']

For most projects that inf-ruby-console-auto can recognize, we try to apply this flag automatically (using command line arguments rather than .irbrc), but some cases remain where the users will have to do it manually.

• IRB doesn't show the prompt after you send some input until you press RET again? And C-x C-e freezes in Ruby buffers?

IRB 1.2.x broke the --noreadline support (#137, IRB#127). Upgrade to IRB 1.3.0 or newer for better experience.

• Pry raises ZeroDivisionError in lib/pry/pager.rb?

  Put Pry.config.pager = false if ENV["INSIDE_EMACS"] into your ~/.pryrc.

• Pry prints �[0G right after start?

  Put Pry.config.correct_indent = false if ENV["INSIDE_EMACS"] into your ~/.pryrc.

Please report problems at http://github.com/nonsequitur/inf-ruby/issues.