Ruby

We'll show here how to configure Emacs as a productive environment for Ruby and Rails development.

Be also aware that Starter Kits like Prelude have many stuff pre-installed, and that Spacemacs has a Ruby layer.

ruby-mode

ruby-mode provides basic font-locking, indentation and navigation support for Ruby source code. It was first included in Emacs 23 (previously it was a third party package, maintained by Ruby's developers). While ruby-mode is fairly barebone package it could be augmented by a multitude of minor modes (see below).

ruby-end - auto insert end statements

Just install ruby-end (in ELPA). Now ruby-end-mode will start alongside ruby-mode.

Ruby on Rails

Rinari

Rinari (in melpa) stands for Rinari Is Not A Rails IDE. It is an Emacs minor mode for Rails that is actively maintained.

Rinari features:

• for 'jumps' between Model, View, Controller and their RSpec examples and Test Unit tests,
• as well as Cucumber steps and features.
• running of a console session with full Rails application loaded for interactive use,
• SQL console,
• starting of the web server (rails server).

For a list of keybindings, see Rinari. The official documentation is alright, but for best information check out the source.

Projectile-rails - navigation, rake tasks, console, etc

Projectile is a popular project management system. It allows to easily search files under a project, switch buffers pertaining to that project, switch to tests files, search in project (with rgrep, ag,…), and more. Now we can add Rails support with projectile-rails (in melpa).

With Projectile Rails you are able to:

• navigate through rails resources (controllers, views, helpers and so on)
• jump to ruby classes and template files
• run rake
• run rails console
• run rails dbconsole
• run rails generate
• run rails server
• open log files with auto-revert-mode on
• see rails keywords highlighted
• take advantage of zeus and spring preloaders

It can be a replacement for rinari.

Intelligent code navigation and completion with Robe

Robe (in MELPA) is a code assistance tool that uses a Ruby REPL subprocess with your application or gem code loaded, to provide information about loaded classes and modules, and where each method is defined.

To load it with ruby-mode:

(require 'robe)
(add-hook 'ruby-mode-hook 'robe-mode)

If you are using rvm you may want to instruct robe to auto-trigger rvm-activate-corresponding-ruby:

(defadvice inf-ruby-console-auto (before activate-rvm-for-robe activate)
  (rvm-activate-corresponding-ruby))

Code navigation

By default bound to M-. (robe-jump). It can be used to jump to definitions of various classes and methods.

Code completion

For intelligent completion robe can be integrated with company mode. Company mode is a modern and modular completion system for emacs which accepts a multitude of pluggable back-ends and front-ends to provide rich completions on the fly. Robe provides a backend to the completion in form of company-robe. This can be configured as follows :

(global-company-mode t)
(push 'company-robe company-backends)

Now all you have to do is hit robe-start when you navigate into your project. After that at any point if you trigger company-robe you should be greeted with an intellisense like method definitions.

Completion will start automatically after you type a few letters. Use M-n, M-p, <tab> and <return> to complete. Search through the completions with C-s, C-r and C-o. Even the documentations are available right from the editor (Press F1 at any menu entry).

Syntax checking: flymake

See Flymake, and install flymake-ruby (in melpa).

To make sure it is started along with ruby mode, add:

(require 'flymake-ruby)
(add-hook 'ruby-mode-hook 'flymake-ruby-load)

Ruby shell inside Emacs

inf-ruby provides a REPL buffer connected to a Ruby subprocess. It is available through the package manager. To bind to a shortcut, do something like:

(global-set-key (kbd "C-c r r") 'inf-ruby)

See also: Shell

RVM integration

Pick rvm.el. Once installed you will just have to call rvm-activate-corresponding-ruby and rvm.el will automatically pick up your ruby version and gemset from your .rvmrc file.

For a keybinding:

(global-set-key (kbd "C-c r a") 'rvm-activate-corresponding-ruby)

See also

You might want to check the following pages to make the most out of Emacs:

• Git, Github and Gitlab
• Buffer_management, code Folding,
• how Emacs helps in Discoverability,
• Compilation and Shell

External links

ruby-mode at Ruby's Subversion repo