public function add_assign_info($cmid, $cmname, $sectionname, $timedue, $submissioninfo, $gradeinfo) {
        $this->assignments[] = array('cmid'=>$cmid,
                               'cmname'=>$cmname,
                               'sectionname'=>$sectionname,
                               'timedue'=>$timedue,
                               'submissioninfo'=>$submissioninfo,
                               'gradeinfo'=>$gradeinfo);
    }