private function createCache(array $config, ContainerBuilder $container)
    {
        $type = $config['type'];
        if (array_key_exists($type, $this->cacheFactories)) {
            $id = sprintf('tbbc_cache.%s_cache', $config['name']);
            $this->cacheFactories[$type]->create($container, $id, $config);

            return $id;
        }

        // TODO: throw exception ?
    }