+ /**
+ * @var Sabre_DAVACL_IPrincipalBackend|null
+ */
+ private static $intstance = null;
+
+ /**
+ * @static
+ * @return Sabre_DAVACL_IPrincipalBackend
+ */
+ public static function &getInstance() {
+ if (is_null(self::$intstance)) {
+ $authBackend = Sabre_DAV_Auth_Backend_Std::getInstance();
+ self::$intstance = new Sabre_DAVACL_PrincipalBackend_Std($authBackend);
+ }
+ return self::$intstance;
+ }
+