作为一个WordPress初学者我正在创建菜单，也想定制<li>标签，以便能够通过CSS分配不同的类名来控制特定的行为，因此我使用custom walker来获得一个带有干净标记的列表，我在这里找到：
https://gist.github.com/toscho/1053467

class T5_Nav_Menu_Walker_Simple extends Walker_Nav_Menu
{
/**
* Start the element output.
*
* @param string $output Passed by reference. Used to append additional content.
* @param object $item Menu item data object.
* @param int $depth Depth of menu item. May be used for padding.
* @param array $args Additional strings.
* @return void
*/
public function start_el( &$output, $item, $depth, $args )
{
$output .= '<li>';
$attributes = '';
! empty ( $item->attr_title )
// Avoid redundant titles
and $item->attr_title !== $item->title
and $attributes .= ' title="' . esc_attr( $item->attr_title ) .'"';
! empty ( $item->url )
and $attributes .= ' href="' . esc_attr( $item->url ) .'"';
$attributes = trim( $attributes );
$title = apply_filters( 'the_title', $item->title, $item->ID );
$item_output = "$args->before<a $attributes>$args->link_before$title</a>"
. "$args->link_after$args->after";
// Since $output is called by reference we don't need to return anything.
$output .= apply_filters(
'walker_nav_menu_start_el'
, $item_output
, $item
, $depth
, $args
);
}
/**
* @see Walker::start_lvl()
*
* @param string $output Passed by reference. Used to append additional content.
* @return void
*/
public function start_lvl( &$output )
{
$output .= '<ul class="sub-menu">';
}
/**
* @see Walker::end_lvl()
*
* @param string $output Passed by reference. Used to append additional content.
* @return void
*/
public function end_lvl( &$output )
{
$output .= '</ul>';
}
/**
* @see Walker::end_el()
*
* @param string $output Passed by reference. Used to append additional content.
* @return void
*/
function end_el( &$output )
{
$output .= '</li>';
}
}

字符串
代码工作得很好。但是现在，当我想通过“Css classes”为菜单中的一个项目添加可选类时，它不起作用。