Everything is a method in ruby, including if and else. Set from YAML

YAML config & if+else returns

#USE IF/ELSE TO SET @config
@config ||= if ENV['fb_client_id'] && ENV['fb_client_secret'] && ENV['fb_scope'] && ENV['fb_canvas_url']
        {
          :client_id     => ENV['fb_client_id'],
          :client_secret => ENV['fb_client_secret'],
          :scope         => ENV['fb_scope'],
          :canvas_url    => ENV['fb_canvas_url']
        }
      else
        YAML.load_file("#{Rails.root}/config/facebook.yml")[Rails.env].symbolize_keys
      end

#THE YAML LOOKS LIKE THIS
development: &defaults
  client_id: 610477565632318
  client_secret: 1b6329dd8984966b75a84c54d76e542c
  scope: user_about_me,friends_about_me,user_activities,friends_activities,user_birthday,friends_birthday,user_checkins,friends_checkins,user_education_history,friends_education_history,user_events,friends_events,user_groups,friends_groups,user_hometown,friends_hometown,user_interests,friends_interests,user_likes,friends_likes,user_location,friends_location,user_notes,friends_notes,user_online_presence,friends_online_presence,user_photo_video_tags,friends_photo_video_tags,user_photos,friends_photos,user_questions,friends_questions,user_relationships,friends_relationships,user_relationship_details,friends_relationship_details,user_religion_politics,friends_religion_politics,user_status,friends_status,user_videos,friends_videos,user_website,friends_website,user_work_history,friends_work_history,email,read_friendlists,read_insights,read_mailbox,read_requests,read_stream,xmpp_login,ads_management,create_event,manage_friendlists,manage_notifications,offline_access,publish_checkins,publish_stream,rsvp_event,publish_actions,manage_pages,user_subscriptions #,friend_subscriptions
  canvas_url: http://apps.facebook.com/fbgraph

test:
  <<: *defaults

production:
  <<: *defaults