public function loadJson($filename)
  {
    $result = false;
    if (file_exists($filename) && is_file($filename)) {
      $json = file_get_contents($filename);
      $data = json_decode($json, true);
      if (is_array($data)) {
        foreach ($data as $name => $value) {
          $this->__set($name, $value);
        }
        $result = true;
      }
    }
    return $result;
  }