build_middleware

# File actionpack/lib/action_controller/metal.rb, line 42
      def build_middleware(klass, args, block)
        options = args.extract_options!
        only   = Array(options.delete(:only)).map(&:to_s)
        except = Array(options.delete(:except)).map(&:to_s)
        args << options unless options.empty?

        strategy = NULL
        list     = nil

        if only.any?
          strategy = INCLUDE
          list     = only
        elsif except.any?
          strategy = EXCLUDE
          list     = except
        end

        Middleware.new(klass, args, list, strategy, block)
      end