我想覆盖核心的最近评论小部件的输出。我扩展了WP_Widget_Recent_Comments 进行了所需的更改，它准确地显示了我想要的内容。然而，我现在已经用Monster小部件测试了主题，对于最近的评论小部件应该输出的位置，抛出了一个错误：

Notice: Undefined index: WP_Widget_Recent_Comments in /Users/tfisher/Sites/mysite/dev/wp-includes/widgets.php on line 1319

这是我的扩展类：

Class My_Recent_Comments_Widget extends WP_Widget_Recent_Comments {

    function widget( $args, $instance ) {
        global $comments, $comment;

        $cache = wp_cache_get(\'widget_recent_comments\', \'widget\');

        if ( ! is_array( $cache ) )
            $cache = array();

        if ( ! isset( $args[\'widget_id\'] ) )
            $args[\'widget_id\'] = $this->id;

        if ( isset( $cache[ $args[\'widget_id\'] ] ) ) {
            echo $cache[ $args[\'widget_id\'] ];
            return;
        }

        extract($args, EXTR_SKIP);
        $output = \'\';

        $title = ( ! empty( $instance[\'title\'] ) && isset($instance[\'title\']) ) ? $instance[\'title\'] : __( \'Recent Comments\', \'mysite\' );

        /** This filter is documented in wp-includes/default-widgets.php */
        $title = apply_filters( \'widget_title\', $title, $instance, $this->id_base );

        $number = ( ! empty( $instance[\'number\'] ) && isset($instance[\'number\']) ) ? absint( $instance[\'number\'] ) : 5;
        if ( ! $number )
            $number = 5;

        /**
         * Filter the arguments for the Recent Comments widget.
         *
         * @since 3.4.0
         *
         * @see get_comments()
         *
         * @param array $comment_args An array of arguments used to retrieve the recent comments.
         */
        $comments = get_comments( apply_filters( \'widget_comments_args\', array(
            \'number\'      => $number,
            \'status\'      => \'approve\',
            \'post_status\' => \'publish\'
        ) ) );

        $output .= $before_widget;
        if ( $title )
            $output .= $before_title . $title . $after_title;

        if ( $comments ) {
            // Prime cache for associated posts. (Prime post term cache if we need it for permalinks.)
            $post_ids = array_unique( wp_list_pluck( $comments, \'comment_post_ID\' ) );
            _prime_post_caches( $post_ids, strpos( get_option( \'permalink_structure\' ), \'%category%\' ), false );

            foreach ( (array) $comments as $comment) {
                $output .= \'<div class="recentcomments item clearfix">\';
                if(get_avatar($comment)) {
                    $output .= \'<figure class="pull-left">\';
                    $output .= \'<a href="\' . get_comment_author_url() . \'">\';
                    $output .= get_avatar( $comment, 100 );
                    $output .= \'</a>\';
                    $output .= \'</figure>\';
                    $output .= \'<div class="content">\';
                } else {
                    $output .= \'<div class="content no-img">\';
                }
                $output .= sprintf(_x(\'%1$s on %2$s\', \'widgets\'), get_comment_author_link(), \'<a href="\' . esc_url( get_comment_link($comment->comment_ID) )) . \'">\';
                $output .= get_the_title($comment->comment_post_ID) . \'</a>\';
                $output .= \'</div>\'; // content
                $output .= \'</div>\'; // item
            }
        }
        $output .= $after_widget;

        echo $output;
        $cache[$args[\'widget_id\']] = $output;
        wp_cache_set(\'widget_recent_comments\', $cache, \'widget\');
    }
}