I'm with 5.4.12.. I thought that they are standard part of Perl as of 5.9 !! Documentation is misleading then :)
I'm interested in two things mainly.. and over the years have constanly fiddled with and never came up with satisfing solution to two problems :
1.1 required arguments passed to subs
1.2 requried params when creating objects
1.3 clean debuging

2. In all of those cases I want to be able to prune those checks in production.
It seemed assertion may be the most clean way to do those... but Perl never had assertions..
Oooo ... and third .. do less typing :)