* @param BagOStuff $cache A cache object such as $wgMemc
* @param string $key The cache key
* @param int $expiry The expiry timestamp or interval in seconds
- * @param bool|array $callback The callback for generating the value, or false
+ * @param bool|callable $callback The callback for generating the value, or false
* @param array $callbackParams The function parameters for the callback
* @param array $deps The dependencies to store on a cache miss. Note: these
* are not the dependencies used on a cache hit! Cache hits use the stored