klass

# File actionpack/lib/action_controller/middleware_stack.rb, line 29
      def klass
        if @klass.respond_to?(:call)
          @klass.call
        elsif @klass.is_a?(Class)
          @klass
        else
          @klass.to_s.constantize
        end
      rescue NameError
        @klass
      end