/**
* Returns an instance of AMA_DataHandler.
*
* @param string $dsn - optional, a valid data source name
* @return an instance of AMA_DataHandler
*/
static function instance($dsn = null)
{
$callerClassName = get_called_class();
if (get_class(self::$instance) !== $callerClassName) {
self::$instance = null;
}
if (self::$instance === NULL) {
self::$instance = new $callerClassName($dsn);
} else {
self::$instance->setDSN($dsn);
}
//return null;
return self::$instance;
}
public function disconnect()
{
parent::disconnect();
self::$instance = NULL;
}