I just commited into bleadperl a patch that implements this :
$ ./perl -e 'no 5'
Perls since v5.0.0 too modern--this is v5.9.3, stopped at -e line 1.
BEGIN failed--compilation aborted at -e line 1.
That is, the exact opposite of the current "use VERSION" syntax.
One of the uses I had in mind for it is to put "no 6" at the top of
modules or programs that are too tightly bound to Perl 5 that there
wouldn't be beneficial to port them to Perl 6. B::* or Safe come to
mind. Of course, that would mean that Perl 6 should also recognize and
handle the "no 6" idiom. That's why I'm cc:ing p6l.
Comments ?
The patch can be found at
http://public.activestate.com/cgi-bin/perlbrowse?patch=25344
