public function load_choices() {
        global $CFG;

        if (is_array($this->choices)) {
            return true;
        }
        $this->choices = array();
        $this->choices[''] = get_string('disable');

        $authsenabled = get_enabled_auth_plugins(true);

        foreach ($authsenabled as $auth) {
            $authplugin = get_auth_plugin($auth);
            if (!$authplugin->can_signup()) {
                continue;
            }
            // Get the auth title (from core or own auth lang files)
            $authtitle = $authplugin->get_title();
            $this->choices[$auth] = $authtitle;
        }
        return true;
    }