💎 Ruby

Updated at 2016-04-07 03:00

Bundler is a tool that manages gem dependencies for your application. You specify a Gemfile with a list of all your dependencies.

# Gemfile example
source ""   # From where to download gems.
ruby "2.2.2"                    # Ruby version.

gem 'gem-name'                  # Installs latest if no Gemfile.lock
gem 'gem-name', '3.0.0.beta3'   # Specific version
gem 'gem-name', '>=1.0'         # Version must be over or equal to 1.0
gem 'gem-name', '~>2.0.3'       # ~> 2.0.3 is identical to >= 2.0.3 and < 2.1
gem 'gem-name', '~> 2.1'        # ~> 2.1 is identical to >= 2.1 and < 3.0

# Gems for a specific environment.
group :development do
  gem 'gem-name'

# Gems from a specific source.
source "" do
  gem 'gem-name'

# Sometimes gem packages and Ruby require statement path are different
gem 'gem-name', :require => 'gem/name'
gem 'rspec',    :require => false  # Installs the gem but doesn't require it

# Sometimes you have a custom location for a gem.
gem 'gem-name', git:    ''
gem 'gem-name', github: 'user/gem-name'
gem 'gem-name', git:    'git://', ref: '0eec4'
gem 'gem-name', path:   '~/gemz/gem-name'

You install all dependencies with bundle install. Will use Gemfile.lock if it is found, Gemfileif not found. The firstbundle installonGemfilewill generate the lockfile and you can update gems in it withbundle update`

bundle install
bundle update gem-name
bundle install --local  # Save gems inside the project, to vendor/cache.
bundle exec file.rb     # Non-rails Ruby requires special execution command.

Binstubs are scripts that are executed in bundler context. Rails stores binstubs in bin directory.

# Usually these are the same inside a project.
bundle exec rails

Don't remove the Gemfile.lock from version control. This is not some randomly generated file - it makes sure that all of your team members get the same gem versions with bundle install.

Separate gems to groups for development or testing in the Gemfile.

Separate gems for OS X and Linux when necessary. Otherwise Gemfile.lock will keep changing all the time.

# Gemfile
group :darwin do
  gem "rb-fsevent"
  gem "growl"

group :linux do
  gem "rb-inotify"

# and add config/application.rb
platform = RUBY_PLATFORM.match(/(linux|darwin)/)[0].to_sym

Use only established gems in your projects. If you're contemplating on including some little-known gem you should do a careful review of its source code first.