Description: ------------ Here is the source code function finish($str) { switch ($this->unknowns) { case "remove": $str = preg_replace('/{[^ \t\r\n}]+}/', "", $str); break; case "comment": $str = preg_replace('/{([^ \t\r\n}]+)}/', "<!-- Template $handle: Variable \\1 undefined -->", $str); break; } return $str; } see that ? in case "comment" here is a variable $handle undefined Expected result: ---------------- Notice: Undefined variable: handle in D:\www\example\inc\PHPLIB.php on line 417