The apprentice takes a shot at expanding on D'oh!, just to make sure he's been paying attention...

Presumeably because push appends the element to the array and use lib prepends it.

The first would, I think, work when you've installed a module into your local area that is already available in the standard area. Why would you do this? Perhaps you need (want) to use (or experiment with) a later version. Perhaps you're not the admin and the real admin is busy, lazy, or charges you to install stuff. Perhaps the existing one is severely broken for some reason (e.g. a bad install). Perhaps you're trying to make sure your stuff is searched before anything else.

The latter is, I believe the preferred approach and should be used unless you know why it won't work for you.

--f