public static function var_names_from_context($classname, $pluginname = '') {
        $pluginname = trim($pluginname);
        if (!empty($pluginname)) {
            $categoryvar = $classname . '_' . $pluginname . '_category';
            $purposevar = $classname . '_' . $pluginname . '_purpose';
        } else {
            $categoryvar = $classname . '_category';
            $purposevar = $classname . '_purpose';
        }
        return [
            $purposevar,
            $categoryvar
        ];
    }