new

# File actionpack/lib/action_dispatch/middleware/stack.rb, line 9
      def initialize(klass_or_name, *args, &block)
        @klass = nil

        if klass_or_name.respond_to?(:name)
          @klass = klass_or_name
          @name  = @klass.name
        else
          @name  = klass_or_name.to_s
        end

        @classcache = ActiveSupport::Dependencies::Reference
        @args, @block = args, block
      end