void TimeBasedRollingFileAppender::open(std::ios_base::openmode mode)
{
  scheduledFilename = helpers::getFormattedTime(filenamePattern, helpers::now(), false);
  if (filename.empty())  // If this method is called from rollover, the filename is not empty, so it will remain unchanged.
    filename = scheduledFilename;
  
  tstring currentFilename = filename;
   ....
}