public function set_config($name, $value) {
        $pluginname = $this->get_name();
        $this->load_config();
        if ($value === NULL) {
            unset($this->config->$name);
        } else {
            $this->config->$name = $value;
        }
        set_config($name, $value, "enrol_$pluginname");
    }