/**
* Push a reference on to the list (fifo, lifo, etc)
*
* This automatically sorts the list after all other requiresments have been met
*
* @return int|null Count of new list, null if restrictions are not met
*
*/
public function pushReference(&$a)
{
if (parent::push($a)) {
array_push($this->list, $a);
usort($this->list, array($this, 'cmp'));
return true;
}
return null;
}
