Random Ruby tips from trenches #1

Hemant's avatar


  1. Rubocop and Flycheck :

Flycheck is a emacs mode which helps us with IDE like warnings in Emacs. I am already using enh-ruby-mode which helps with some of the syntax errors and stuff, but what is nice about flycheck is it integrates with rubocop and shows rubocop errors in-place in the editor.

A picture is worth thousand words so:

rubocop with flycheck

  1. pry ––gem:

pry --gem opens a pry session with ./lib added to $LOAD_PATH and 'require's the gem. A good shortcut while working on gems and you want a quick console with the gem loaded.

  1. ruby –S :

This can be used for running binaries which are present in local directory. For example, if you are working on bundler and want to run bundle command with local version of bundler rather than one installed globally you can use:

ruby -S ./bin/bundle -I ./lib/ install

The advantages are:

  • ruby -S allows you to ignore #!/usr/bin/env ruby line and even if current version of ruby is X using ruby -S you can run the command with another version of Ruby. Especially useful for running scripts with JRuby, Rbx etc.

  • Based on RUBYPATH environment variable running a script via ruby -S (or jruby -S) allows PATH environment to be modified. For example running jruby -S gem does not run gem which is in current path, but it runs gem command provided by JRuby because JRuby defines different RUBYPATH.

  1. Faster rbenv load :

If you are using rbenv and there is a lag while opening a new shell, consider updating the rbenv initializing line in your shell profile to:

eval "$(rbenv init - --no-rehash)"

The --no-rehash flag tells rbenv to skip automatic rehash when opening a new shell and speeds up the process. This also speeds up VIM if you are using vim-rails or vim-ruby.