/// <summary> /// delete one trainee /// </summary> /// <param name="trainee"></param> public void DeleteTrainee(Trainee trainee) { if (DataSource.trainees.RemoveAll(item => item.Id == trainee.Id) == 0) { throw new Exception("failed to remove, trainee with the same ID not found"); } Dal_XML_imp.DeleteTrainee(trainee); traineeEvent(this, null); }