Для prestashop 1.6
Добавить новую переменную в класс /override/classes/Product.php
class Product extends ProductCore
{
public $newVar;
public function __construct($id_product = null, $full = false, $id_lang = null, $id_shop = null, Context $context = null)
{
Product::$definition['fields']['newVar'] = array('type' => self::TYPE_HTML, 'lang' => true, 'validate' => 'isString');
parent::__construct($id_product, $full, $id_lang, $id_shop, $context);
}
}