On 18 Jul 2002 at 23:39, belg4mit wrote:
> Heh I just came across this today. It's an interesting optimization,
> but does it occur that often? It also precludes the possiblity of action at a
> distance / more complicated sort blocks/subroutines doing more than just
> sorting...
>
> Peter Makholm wrote:
> >
> > xyzzy% perl -le 'sort {print "a:$a\tb:$b"; $a cmp $b} qw(5 2 3 4 1)'
> > xyzzy%
> >
> > Somehow the print statement isn't evaled. Playing a little more around
> > I tried the following:
> >
> > xyzzy% perl -le '(sort {print "a:$a\tb:$b"; $a cmp $b} qw(5 2 3 4 1))'
> > xyzzy% perl -le '(sort {print "a:$a\tb:$b"; $a cmp $b} qw(5 2 3 4 1))[3]'
> > a:2 b:5
[...]
What's the trick here --- is it that the sort isn't done *at*all* [it isn't
that the side-effects aren't happening, but that the *SORT* isn't happening]?
If so, that's pretty interesting --- how many other actions/operators just "go
away" when evaluated in a void context ... Does a map in void context actually
happen?
/Bernie\
--
Bernie Cosell Fantasy Farm Fibers
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--> Too many people, too few sheep <--
