for($/)x16
A slick way of getting the newline (vis-à-vis -l print until...)!
Changing the loop to for($_)x16 is informative.
And, since a bare print prints both $_ and $/, I found it rather unobvious which variable holds the strings.
Actually, $/ is the input record
separator, so a bare print does not print it.
What's being printed is just the (localized) $_
inside the for loop.
Of course, a bare print will print $\, aka the output
record separator, often seen in golf,
as in, for example, The golf course looks great, my swing feels good, I like my chances (Part I).
The for($/)x16 loop aliases $/ and,
despite the x16, only the single $/ value
is (repeatedly) changed, as you will discover by printing it
after the loop has terminated.
Replacing "print" with "warn" like so:
s/^|\d+/$&+$'||1/eg,warn("du='$_' ds='$/'\n"),s// /for($/)x16;
warn("at end du='$_' ds='$/'\n");
should clarify.
BTW, this eccentric "for loop aliasing" trick is
often seen in golf; see, for example, Drunk on golf: 99 Bottles of Beer
in the "Bottle Golf Tip No 2" section (search for
Cantor).
Finally, the "for loop aliasing" trick is a specific
example of Eugene van der Pijll's general golfing mantra,
"Can't possibly work, let's try it anyway". :)
| [reply]
[d/l]
[select] |
Doh, I flubbed that ($/ vs. $\). I so often print$/,/expr/?this:that, I confused myself.
And darn you - I had already read your lengthy linked topics, and perhaps all of their references, but I find them irresistable! This time through, I most enjoyed this gem:
s///ge>>9?print:do$0
The :do$0 is one *sick* loop. And the return value from s/// idea gave me the following "for 1 to 15" method:
perl -le'$_=1;{print,s/(\d+) ?/+$1 $1/g,s/\S+/$&/eeg>16||redo}'
A couple more tricks for me! | [reply]
[d/l]
[select] |
Yes, I too find the "do$0" loop hilarious.
A great write-up of its use in the 2002 Kolakoski game by good ol' Rick Klement
can be found
here
and also in Mtv's book of golf (page 105).
I believe Ton Hospel was the first person to
use the eccentric "do$0" loop in a golf competition.
And thanks for the "redo" tip; I'd forgotten about
redo after all these years. :)
Update: Just noticed another Rick Klement gem where he concludes with: Lesson to be learned: try something before you say "that can't work" ...
which looks like an independent invention of Eugene van der Pijll's famous golfing aphorism: Can't possibly work, let's try it anyway. :)
| [reply] |