protected function _normalizeVar($var, $includeSeparator = false)
    {
        if ($includeSeparator) {
            $var = explode(NAMESPACE_SEPARATOR, $var);
        }

        $vars = (array) $var;

        $pattern = "/[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/";

        foreach ($vars as $var) {
            if ($var != '' && !preg_match($pattern, $var)) {
                throw new ClassWrapperException(sprintf('Syntax error: \'%s\'', $var));
            }
        }

        return implode(($includeSeparator) ? NAMESPACE_SEPARATOR : '', $vars);
    }