/**
  * Get attribute taxonomies. Taxonomies are lazy loaded.
  *
  * @return  array of stdClass objects representing attributes
  */
 public static function getAttributeTaxonomies()
 {
     global $wpdb;
     if (self::$attribute_taxonomies === null) {
         self::$attribute_taxonomies = $wpdb->get_results("SELECT * FROM " . $wpdb->prefix . "fflcommerce_attribute_taxonomies;");
     }
     return self::$attribute_taxonomies;
 }