<?php if (!defined('ABSPATH')) die('No direct access allowed'); final class WOOF_EXT_SELECT_HIERARCHY extends WOOF_EXT { public $type = 'html_type'; public $html_type = 'select_hierarchy'; //your custom key here public $html_type_dynamic_recount_behavior = 'single'; public function __construct() { parent::__construct(); $this->init(); } public function get_ext_path() { return plugin_dir_path(__FILE__); } public function get_ext_override_path() { return get_stylesheet_directory() . DIRECTORY_SEPARATOR . "woof" . DIRECTORY_SEPARATOR . "ext" . DIRECTORY_SEPARATOR . $this->html_type . DIRECTORY_SEPARATOR; } public function get_ext_link() { return plugin_dir_url(__FILE__); } public function woof_add_html_types($types) { $types[$this->html_type] = esc_html__('Hierarchy drop-down', 'woocommerce-products-filter'); return $types; } public function init() { } } WOOF_EXT::$includes['taxonomy_type_objects']['select_hierarchy'] = new WOOF_EXT_SELECT_HIERARCHY();