我正在尝试在wp\\U list\\U页面创建的列表上设置交替类。

目前，我已经扩展了Walker\\u page类，更新了start\\u el函数，如下所示：

class Sidebar_walker extends Walker_page {

var $alternate = \'background_1\';

function start_el( &$output, $page, $depth, $args, $current_page = 0 ) {
    if ( $depth )
        $indent = str_repeat("\\t", $depth);
    else
        $indent = \'\';

    extract($args, EXTR_SKIP);
    $css_class = array(\'page_item\', \'page-item-\'.$page->ID);

    $alternate = ($alternate != \'background_1\') ? \'background_1\' : \'background_2\';
    $css_class[] = $alternate;

    if ( !empty($current_page) ) {
        $_current_page = get_post( $current_page );
        if ( in_array( $page->ID, $_current_page->ancestors ) )
            $css_class[] = \'current_page_ancestor\';
        if ( $page->ID == $current_page )
            $css_class[] = \'current_page_item\';
        elseif ( $_current_page && $page->ID == $_current_page->post_parent )
            $css_class[] = \'current_page_parent\';
    } elseif ( $page->ID == get_option(\'page_for_posts\') ) {
        $css_class[] = \'current_page_parent\';
    }

    $css_class = implode( \' \', apply_filters( \'page_css_class\', $css_class, $page, $depth, $args, $current_page ) );

    $output .= $indent . \'<li class="\' . $css_class . \'"><a href="\' . get_permalink($page->ID) . \'">\' . $link_before . apply_filters( \'the_title\', $page->post_title, $page->ID ) . $link_after . \'</a>\';

    if ( !empty($show_date) ) {
        if ( \'modified\' == $show_date )
            $time = $page->post_modified;
        else
            $time = $page->post_date;

        $output .= " " . mysql2date($date_format, $time);
    }
}
}