append_features

# File lib/rss/trackback.rb, line 30
    def append_features(klass)
      super

      unless klass.class == Module
        klass.module_eval {include TrackBackUtils}

        klass.install_must_call_validator(TRACKBACK_PREFIX, TRACKBACK_URI)
        %(ping).each do |name|
          var_name = "#{TRACKBACK_PREFIX}_#{name}"
          klass_name = "TrackBack#{Utils.to_class_name(name)}"
          klass.install_have_child_element(name, TRACKBACK_URI, "?", var_name)
          klass.module_eval(            remove_method :#{var_name}            def #{var_name}              @#{var_name} and @#{var_name}.value            end            remove_method :#{var_name}=            def #{var_name}=(value)              @#{var_name} = Utils.new_with_value_if_need(#{klass_name}, value)            end, __FILE__, __LINE__)
        end

        [%(about s)].each do |name, postfix|
          var_name = "#{TRACKBACK_PREFIX}_#{name}"
          klass_name = "TrackBack#{Utils.to_class_name(name)}"
          klass.install_have_children_element(name, TRACKBACK_URI, "*",
                                              var_name)
          klass.module_eval(            remove_method :#{var_name}            def #{var_name}(*args)              if args.empty?                @#{var_name}.first and @#{var_name}.first.value              else                ret = @#{var_name}.__send__("[]", *args)                if ret.is_a?(Array)                  ret.collect {|x| x.value}                else                  ret.value                end              end            end            remove_method :#{var_name}=            remove_method :set_#{var_name}            def #{var_name}=(*args)              if args.size == 1                item = Utils.new_with_value_if_need(#{klass_name}, args[0])                @#{var_name}.push(item)              else                new_val = args.last                if new_val.is_a?(Array)                  new_val = new_value.collect do |val|                    Utils.new_with_value_if_need(#{klass_name}, val)                  end                else                  new_val = Utils.new_with_value_if_need(#{klass_name}, new_val)                end                @#{var_name}.__send__("[]=", *(args[0..-2] + [new_val]))              end            end            alias set_#{var_name} #{var_name}=, __FILE__, __LINE__)
        end
      end
    end