/**
  * Main class methode
  * @return mixt null or error object in case of error;
  * @access public
  */
 function Execute()
 {
     if ($this->validReplacement === false) {
         $ret = new tNG_error("FOLDER_DEL_SECURITY_ERROR", array(), array($this->fullFolder, $this->baseFolder));
         return $ret;
     }
     $this->fullFolder = KT_realpath($this->baseFolder . $this->folder);
     // security
     if (substr($this->fullFolder, 0, strlen($this->baseFolder)) != $this->baseFolder) {
         $ret = new tNG_error("FOLDER_DEL_SECURITY_ERROR", array(), array($this->fullFolder, $this->baseFolder));
         return $ret;
     }
     $ret = null;
     if (!file_exists($this->fullFolder)) {
         return $ret;
     }
     $folder = new KT_Folder();
     // delete thumbnails;
     $folder->deleteFolderNR($this->fullFolder);
     if ($folder->hasError()) {
         $arr = $folder->getError();
         $ret = new tNG_error("FOLDER_DEL_ERROR", array($arr[0]), array($arr[1]));
         return $ret;
     }
     return $ret;
 }