/**
  * Set $uid variable
  *
  * @param int $uid
  * @see getUID()
  * @uses iCalToDo::$uid
  * @uses iCalToDo::$startdate
  * @uses iCalToDo::$summary
  */
 private function setUID($uid = 0)
 {
     if (strlen(trim($uid)) > 0) {
         $this->uid = (string) $uid;
     } else {
         $rawid = (string) $this->startdate . 'plus' . parent::getSummary();
         $this->uid = (string) md5($rawid);
     }
 }