20 of my favorite Ruby gems, explained in 15 seconds per slide.

1. authlogic
class UserSession < Authlogic::Session::Base
end
class ApplicationController < ActionController::Base
private
def current_user_session
UserSession.find
end
def current_user
current_user_session && current_user_session.record
end
binarylogic

2. bcrypt-ruby
require 'bcrypt'
class User < ActiveRecord::Base
# users.password_hash in the database is a :string
include BCrypt
def password
@password ||= Password.new(password_hash)
end
def password=(new_password)
@password = Password.create(new_password)
self.password_hash = @password
end
end
codahale

3. capybara
describe "the signup process", :type => :request do
before :each do
User.make(:email => 'user@ex.com', :password => 'caplin')
end
it "signs me in" do
within("#session") do
fill_in 'Login', :with => 'user@example.com'
fill_in 'Password', :with => 'password'
end
click_link 'Sign in'
end
end
jnicklas

4. dim
GameContainer = Dim::Container.new
GameContainer.register(:environment) { ENV['EXP_ENV'] }
GameContainer.register(:transmitter) do |c|
Transmitter.new(c.environment)
end
jimweirich (gem-ified by me)

5. factory_girl
Factory.define :simple_map, :parent => :map do |m|
m.name "Simple Map"
m.size 5
m.after_create do |map|
map.with_grid do |grid|
grid.add_feature(Terrain::Dirt,1,1,3,3)
grid.add_feature(MapObjects::BlueCrystal,1,1)
grid.add_feature(Landmarks::Mountain,4,4)
end
end
end
context "saving and restoring" do
it "preserves all data types in the grid" do
map = Factory(:simple_map)
map.feature_at(1,1).terrain.name.should == Terrain::Dirt
end
end
thoughtbot

6. foreigner
add_foreign_key :maps, :terrain, :column => :default_terrain_id
matthuhiggins

7. formtastic
%h1 Sign Up
= semantic_form_for @user, :url => signup_path do |form|
= form.semantic_errors
= form.inputs do
= form.input :email, input_html: { autofocus: true }
= form.input :identifier, :label => "In-Game Identifier"
= form.input :password
= form.buttons do
= form.commit_button "Signup"
justinfrench

8. girl_friday
QUEUE = GirlFriday::WorkQueue.new(:user_email, :size => 3) do |m|
UserMailer.registration_email(m).deliver
end
# while handling a web request
QUEUE.push(:email => @user.email, :name => @user.name)
mperham

9. grb
=> create new branch `branch`
$ grb new [branch]
=> track branch
$ grb track `branch`
=> add a remote repo
$ grb remote_add `name` `repo path`
=> remove a remote repo
$ grb remote_rm `name`
jinzhu

10. guard (guard-*)
guard 'bundler' do
watch('Gemfile')
end
guard 'rspec' do
watch(%r{^spec/.+_spec.rb})
watch(%r{^lib/(.+).rb}) { |m| "spec/lib/#{m[1]}_spec.rb" }
watch('spec/spec_helper.rb') { "spec" }
end
guard 'coffeescript', :output => 'public/js/compiled' do
watch(%r{^app/coffeescripts/.+.coffee})
end
thibaudgg

11. jammit
embed_assets: on
gzip_assets: on
javascript_compressor: yui
javascripts:
workspace:
- public/javascripts/vendor/jquery.js
- public/javascripts/lib/*.js
- public/javascripts/views/**/*.js
- app/views/workspace/*.jst
stylesheets:
common:
- public/stylesheets/reset.css
- public/stylesheets/widgets/*.css
workspace:
- public/stylesheets/pages/workspace.css
empty:
- public/stylesheets/pages/empty.css
documentcloud

12. omniauth
require 'oa-oauth'
use OmniAuth::Strategies::Twitter, 'KEY', 'SECRET'
# redirect user to /auth/twitter
# twitter redirects user to /auth/twitter/callback
get '/auth/twitter/callback' do
auth_hash = request.env['omniauth.auth']
end
intridea

13. ostruct*
require 'ostruct'
record = OpenStruct.new
record.name = "John Smith"
record.age = 70
record.pension = 300
puts record.name # -> "John Smith"
puts record.address # -> nil
*part of stdlib

14. perftools.rb
tmm1

15. pg_sexy_constraints
class AddConstraintsToBooks < ActiveRecord::Migration
def self.up
constrain :books do |t|
t.title :not_blank => true, :alphanumeric => true
t.isbn :unique => true, :blacklist => %w(badbook1)
end
end
end
maxim

16. pusher
# server
Pusher['a_channel'].trigger!('an_event', {:some => 'data'})
# client-side JS
var pusher = new Pusher('API_KEY');
pusher.subscribe('a_channel');
pusher.bind('an_event',
function(data) {
console.info(data.some); // “data”
}
);
pusher

17. right_aws
query = ["['cat'=?] union ['dog'=?]", "clew", "Jon's boot"]
sdb.query('family', query)
queue = RightAws::SqsGen2::Queue.create(sqs, 'my_cool_queue')
msg = queue.receive
msg.visibility = 0
queue.clear(true)
queue.send_message('example')
msg2 = queue.pop
rightscale

18. spork
Guard is now watching at '/Users/subelsky/code/exp-world'
Starting Spork for RSpec
Spork server for RSpec successfully started
Guard::RSpec is running, with RSpec 2!
Running all specs
Using RSpec
Loading Spork.prefork block...
........................................................
Finished in 2 seconds
74 examples, 0 failures
URL

19. therubyracer
require 'v8'
cxt = V8::Context.new
cxt.eval('parseInt("50",10)') # => 50
cxt["say"] = lambda { |word, times| word * times }
cxt.eval("say('Hello', 3)") # => HelloHelloHello
cowboyd

20. timecop
joe = User.find(1)
joe.purchase_home()
assert !joe.mortgage_due?
# move ahead a month and assert that the mortgage is due
Timecop.freeze(Date.today + 30) do
assert joe.mortgage_due?
end
jtrupiano