control verbose mode in Portfile?

[René J . V . Bertin]

Hi,

Out of curiosity: is it possible to control verbose mode in a Portfile, like 
with `set +x` / `set -x` in shell scripts?

I'd be interested to use that in the post-activate block of a number of my 
ports, as an easy way to give a little more feedback to the user.

Thanks,
R.