callback

# File activerecord/lib/active_record/associations/collection_association.rb, line 499
        def callback(method, record)
          callbacks_for(method).each do |callback|
            case callback
            when Symbol
              owner.send(callback, record)
            when Proc
              callback.call(owner, record)
            else
              callback.send(method, owner, record)
            end
          end
        end