/**
* Creates a singleton session of the given type. Some session types
* (native, database) also support restarting a session by passing a
* session id as the second parameter.
*
* @param string type of session (native, cookie, etc)
* @param string session identifier
* @return Session
*/
public static function getInstance($id = NULL)
{
if (self::$instance === false) {
// Create a new session instance
self::$instance = $session = new self($id);
// Write the session at shutdown
register_shutdown_function(array($session, 'write'));
}
return self::$instance;
}
