Autoloading modules from lib directory in Rails 3/4

autoload_modules_rails_4.rb

# Let's say we want a Shipping module
config.autoload_paths << Rails.root.join('lib', 'shipping')

# Then it's all about naming conventions
# In lib/shipping/shipping.rb
module Shipping
end

# Then let's say you want a Client class that will be accessible through Shipping::Client
# In lib/shipping/client.rb
class Client
end