<? class A { private $_count = ""; static private $_instance = null; private function __construct( ) { } public function showCount() { echo $this->_count; } static public function setCount( $num ) { $obj = self::getInstance(); $obj->_setCount($num); return $obj; } private function _setCount( $num ) { $this->_count += $num; } static private function getInstance() { if ( is_null(self::$_instance) ) self::$_instance = new self(); return self::$_instance; } } A::setCount(5); A::setCount(10)->showCount(); ?>