That all depends ... on whether you manage to get the opener to work ;-)

I'd rather go with a slow function that was fast to write than a fast function that was slow and error prone to write. I can always speed up working code (or, failing that, fall back to the original slow code) much easier than taking fast code and making it work ;-)

(Note - this is in no way intended to say that the above code doesn't work, only that I've seen many people get fooled when trying to use the *dir functions - including myself.)