function db_cart_handler($cart_id)
	{
	  parent :: cart_handler($cart_id);
	  
	  $this->cart_db_table =& db_table_factory :: instance('cart');
	  
	  register_shutdown_function(array(&$this, '_db_cart_handler'));
	}
	function session_cart_handler($cart_id)
	{
	  parent :: cart_handler($cart_id);		
	}