protected function getPath($variableName = '')
    {
        $hash = function ($name) {
            return hash($this->hashingAlgorithm, $name);
        };
        $path = $this->basedir . PHP_DS . $hash($this->namespace);
        if ($variableName) {
            $path .= PHP_DS . $hash($variableName) . '.dat';

            return $path;
        }

        return $path;
    }