enable_by_file

# File railties/lib/rails/dev_caching.rb, line 10
      def enable_by_file
        FileUtils.mkdir_p("tmp")

        if File.exist?(FILE)
          delete_cache_file
          puts "Development mode is no longer being cached."
        else
          create_cache_file
          puts "Development mode is now being cached."
        end

        FileUtils.touch "tmp/restart.txt"
      end