这个widget_display_callback hook接受3个参数，如中所示/wp-includes/widgets.php: ^{（第180行，WP 3.4.2）}

• $instance = apply_filters(\'widget_display_callback\', $instance, $this, $args);

  // Priority = 10 // Arguments = 3
  add_filter(\'widget_display_callback\', \'wpse_57546_widget_display_callback\', 10, 3);
  
  // Using "$this" as an argument produces errors, 
  // as it is a reference to the current object
  // see http://stackoverflow.com/q/1523479/1287812
  // hence it is renamed to "$thiz"
  function wpse_57546_widget_display_callback( $instance, $thiz, $args ) 
  {
      /* Some Code */
      return $instance;
  }
  

  使用FirePHP, 我们看到这个过滤器在前端显示的所有小部件中运行，下面是小部件“类别”的值：

  $instance = array(
      [\'title\'] =>
      [\'count\'] => 0
      [\'hierarchical\'] => 0
      [\'dropdown\'] => 0
  )
  
  $thiz = WP_Widget_Categories(
      id_base = \'categories\'
      name = \'Categories\'
      widget_options = array(
          [\'classname\'] => \'widget_categories\'
          [\'description\'] => \'A list or dropdown of categories\'
      )
      control_options = array(
          [\'id_base\'] => \'categories\'
      )
      number = 2
      id = \'categories-2\'
      updated =
      option_name = \'widget_categories\'
  )
  
  $args = array(
      [\'name\'] => \'Main Sidebar\'
      [\'id\'] => \'sidebar-1\'
      [\'description\'] =>
      [\'class\'] =>
      [\'before_widget\'] => \'<aside id="categories-2" class="widget widget_categories">\'
      [\'after_widget\'] => \'</aside>\'
      [\'before_title\'] => \'<h3 class="widget-title">\'
      [\'after_title\'] => \'</h3>\'
      [\'widget_id\'] => \'categories-2\'
      [\'widget_name\'] => \'Categories\'
  )
  

  您要查找的值在$args:

  $args[\'id\']
  $args[\'widget_id\']
  

  和访问$thiz 值，您可以使用：

  $thiz->id_base
  $thiz->widget_options[\'classname\']