Today I started learning a new language: Ruby! Coming from a JavaScript world, this article helped me a lot (backed-up here, should it ever vanish from the Internet). In this article, I sum up everything I've learned so far. It's a sort of memo for myself.

Learning resources

Ruby

• https://openclassrooms.com/courses/lancez-vous-dans-la-programmation-avec-ruby (French)
• http://tryruby.org: awesome interactive tutoral
• http://rubykoans.com/: learn by doing TDD (Test-Driven Development): make all tests pass

Rails

• http://rubyonrails.org/doctrine/
• CHOOSING RUBY ON RAILS FOR YOUR NEXT WEB DEVELOPMENT PROJECT
• Code School: Rails for Zombies
• Initiez-vous à Ruby on Rails
• Continuez avec Ruby on Rails

Install

Install rbenv. In short, here is how:

sudo apt update && sudo apt install openssl libicu-dev libssl-dev libreadline-dev zlib1g-dev
git clone https://github.com/rbenv/rbenv.git ~/.rbenv
cd ~/.rbenv && src/configure && make -C src
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.zshrc
~/.rbenv/bin/rbenv init
# Open a new shell
mkdir -p "$(rbenv root)"/plugins
git clone https://github.com/rbenv/ruby-build.git "$(rbenv root)"/plugins/ruby-build
rbenv install 2.5.0
rbenv global 2.5.0

# Check everything is installed and correctly set up
curl -fsSL https://github.com/rbenv/rbenv-installer/raw/master/bin/rbenv-doctor | bash

Then, add must-have stuff:

gem install bundler

# In a fresh new Ruby project folder, create a Gemfile
rbenv local 2.5.0 # Set version 2.5.0 for this project, same as .nvmrc for Node projects
bundle init
bundle install --path vendor --binstubs bin # Set up .bundle config to install packages to the local folder
# Add vendor and .bundle to your .gitignore file

# In a Ruby project folder, install all dependencies
bundle install # or simply `bundle`

Upgrade Ruby version

Update the version in Gemfile and .ruby-version. Then run:

cd $HOME/.rbenv/plugins/ruby-build && git pull && cd -
rbenv install
gem install bundler
bundle

Stuff to know

• ; is optional
• parentheses optional in if statements
• == vs ===: https://stackoverflow.com/questions/4467538/what-does-the-operator-do-in-ruby
• puts (adds new line) vs print (no new line)
• .each do |item| ... end
• 10.times do |i| ... end
• if, elsif, else, end
• array = [1,2]
• array[0]
• When you place a colon in front of a simple word, you get a Ruby symbol: :a
• hash = {a:1,b:2} # creates symbols :a and :b
• hash[:a]
• hash['ok'] = 'yolo' # ok is not a symbol
• return statement optional, last line is implicitely returned
• func(a,b) == func a, b
• obj.func == obj.func()
• def initialize ... end
• @classMemberVariable
• def func == def func()
• return true if .... == if ...<line break>return true<line break>end
• Inheritance: class Child < Mother
• Replace first occurrence in string: string['word'] = 'new word'
• ratings = Hash.new(0): all new hashes will default to 0 as their value
• do..end vs curly braces for blocks in Ruby: https://stackoverflow.com/questions/5587264/do-end-vs-curly-braces-for-blocks-in-ruby
• pry: pauses execution but does not give access to local variables
• binding.pry: pauses execution, gives access to local variables but also pauses all threads (server and tests for instance)
• whereami == @ (in binding.pry / pry)
• help (get help in binding.pry /pry)
• PRY_RESCUE_RAIL=1 rails test: runs a test and pauses on falsy assertions

Ranges

• x..y (y included) vs x...y (y not included)

Tests

• assert_equal x,y
• assert_match(/regex/, x)

Resources

• Ruby ampersand colon shortcut
• What does to_proc method mean?
• Closures in Ruby
• What does &. (ampersand dot) mean in Ruby?
• Ruby & (Ampersand) Parameter Demystified
• Ruby 2 Keyword Arguments
• What does a double * (splat) operator do
• What do =~ and /\ mean in Ruby?
• %Q, %q, %W, %w, %x, %r, %s
• Rails Routing from the Outside In
• Multiline strings in Ruby 2.3 - the squiggly heredoc
• Making sense of ActiveRecord joins, includes, preload, and eager_load
• What's the difference between colon “:” and fat arrow “=>”