url_helpers

# File actionpack/lib/action_dispatch/routing/route_set.rb, line 385
      def url_helpers
        @url_helpers ||= begin
          routes = self

          Module.new do
            extend ActiveSupport::Concern
            include UrlFor

            # Define url_for in the singleton level so one can do:
            # Rails.application.routes.url_helpers.url_for(args)
            @_routes = routes
            class << self
              delegate :url_for, :optimize_routes_generation?, :to => '@_routes'
            end

            # Make named_routes available in the module singleton
            # as well, so one can do:
            # Rails.application.routes.url_helpers.posts_path
            extend routes.named_routes.module

            # Any class that includes this module will get all
            # named routes...
            include routes.named_routes.module

            # plus a singleton class method called _routes ...
            included do
              singleton_class.send(:redefine_method, :_routes) { routes }
            end

            # And an instance method _routes. Note that
            # UrlFor (included in this module) add extra
            # conveniences for working with @_routes.
            define_method(:_routes) { @_routes || routes }
          end
        end
      end