user_sinks_user_source.rb

class UserSinksUserSource < ActiveRecord::Base
  belongs_to :user_source, :polymorphic => true
  belongs_to :user_sink,   :polymorphic => true
  
  acts_as_double_polymorphic_join(:user_sources =>[:departments,:roles,:users],
                                  :user_sinks   =>[:restrictions,:sub_requests,:notices])
end