//код по шаблону проектирования Sigleton
class Preferences
  {
  private $props = array();
  private static $instance;
  function __construct() {}
  
  public static function getInstance ()
    {
    if (empty (self::$instance))
      {
      self::$instance = new Preferences();
      }
    return self::$instance;
    }
  
  //Установка свойства
  public function setProperty($key , $val)
    {
    $this->props[$key] = $val;
    }
    
  //Получение свойства
  public function getProperty($key)
    {
    return $this->props[$key];
    }
  }
  
  $pref = Preferences::getInstance();
  $pref->setProperty ("Name",'Иван');
  unset ($pref);
  $pref = Preferences::getInstance();
  echo $pref->getProperty ("Name");