protected function file($key)
    {
        return $this->dir . DIRECTORY_SEPARATOR . $this->key($key) . "." . $this->fileExtension;
    }
protected function file($key)
    {
        return $this->dir . DIRECTORY_SEPARATOR . $this->key($key) . "." . $this->fileExtension;
    }
protected function file ( $ key ) { return $ this -> dir . DIRECTORY_SEPARATOR . $ this -> key ( $ key ) . "." . $ this -> fileExtension ; }
Generates the filename to store based on the cachePrefix and given key

@param string $key The key we'll use to generate our key

@return string A unique filename
Generates the filename to store based on the cachePrefix and given key