protected function bindPartVar($var, $type, ServerRequestInterface $request, array $parts, &$part)
    {
        if (!is_string($var) || $var[0] !== '$') {
            return false;
        }
        
        $options = array_map('trim', explode('|', $var));
        $part = $this->bindVar($type, $request, $parts, $options);
        return true;
    }