It is possible to write a completely self-contained Singleton base class in PHP 5.3 using get_called_class.
<?php
abstract class Singleton {
protected function __construct() {
}
final public static function getInstance() {
static $aoInstance = array();
$calledClassName = get_called_class();
if (! isset ($aoInstance[$calledClassName])) {
$aoInstance[$calledClassName] = new $calledClassName();
}
return $aoInstance[$calledClassName];
}
final private function __clone() {
}
}
class DatabaseConnection extends Singleton {
protected $connection;
protected function __construct() {
// @todo Connect to the database
}
public function __destruct() {
// @todo Drop the connection to the database
}
}
$oDbConn = new DatabaseConnection(); // Fatal error
$oDbConn = DatabaseConnection::getInstance(); // Returns single instance
?>