/**
  * @desc Return the categories manager.
  */
 public static function get_categories_manager()
 {
     if (self::$categories_manager === null) {
         $categories_items_parameters = new CategoriesItemsParameters();
         $categories_items_parameters->set_table_name_contains_items(ForumSetup::$forum_topics_table);
         $categories_items_parameters->set_field_name_id_category('idcat');
         self::$categories_manager = new CategoriesManager(ForumCategoriesCache::load(), $categories_items_parameters);
     }
     return self::$categories_manager;
 }