thanks for the comments, what i m planning to do is.... function _autoload($class) { if($class == 'Database') { if(class_exis('PDO') { include_once('Database_PDO.php'); } else { include_once('Database.php'); } } where in Database_PDO.php contains class Database extends PDO { } Database.php contains class Database { } -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php