I bumped into this feature while reading some of the scripts in the eg/ directory (of the perl installation). A lot of, uhm, interesting code in there :-)

The "fun" thing about this is that it is a feature we all depend on almost every day (hint: module writing).

Oh, the joys of deprecated constructs, perl -e '@a{a,b,c,d} = (); do { print if $_ NE d } for keys a'

*shrug* :-)

Autark.