updater

# File railties/lib/rails/application/routes_reloader.rb, line 32
      def updater
        @updater ||= begin
          dirs = @external_routes.each_with_object({}) do |dir, hash|
            hash[dir.to_s] = %(rb)
          end

          ActiveSupport::FileUpdateChecker.new(paths, dirs) { reload! }
        end
      end