Create temporary function

I have recently run across situations that might benefit from the
ability to create a temporary function.

One situation is where periodic processing would benefit from
server-side functions but the processing is run rarely (say monthly or
annually) and the requirements for the function may change. This is
relatively easily handled by a CREATE OR REPLACE..run..DROP FUNCTION but
CREATE TEMPORARY FUNCTION would be cleaner.

The other is where it would be nice for a client to see an isolated
individual copy of a function.

For me both of the above are minor nice-to-haves. I have no idea how
difficult this would be to implement but in the spirit of brainstorming,
I thought I'd throw it out to see if anyone else thinks it is a useful
concept.

Cheers,
Steve