static function build_visualizer($course, $key = null, $keyid = null, $page = 0, $per_page = 50, $export = false) { global $CFG; $base = $CFG->dirroot . '/blocks/student_gradeviewer/visualizer/'; if (in_array($key, referral_visualizer::types())) { require_once $base . $key . '_visualizer.php'; $class = 'referral_' . $key . '_visualizer'; return new $class($course, $key, $keyid, $page, $per_page, $export); } require_once $base . 'blank_visualizer.php'; return new referral_blank_visualizer($course, 'blank'); }