worley@compass.com (Dale Worley) (03/27/91)
I don't know if this has been hashed over before, but: What is the shortest self-reproducing Perl program? (Well, the null file is, but what is the shortest non-trivial program?) The best I've been able to do is: print @a=<DATA>,@a __END__ print @a=<DATA>,@a __END__ Dale Dale Worley Compass, Inc. worley@compass.com -- So you want to have a shameful affair? Yet, somehow you can't justify it? The next time you are contemplating a decision in which you are debating whether or not to go for the gusto, ask yourself this Important Question: How long will I be dead? With that perspective, you can now make a free, fearless choice to do just about any goddamned sneaky thing your devious little mind can think up. Go ahead. Have your fun. You're welcome. Go on. See you in Hell. --Matt Groening
flee@cs.psu.edu (Felix Lee) (03/27/91)
Here's a shorter non-null self-reproducing program: print<DATA>x 2 __END__ print<DATA>x 2 __END__ And here's one shorter, but less portable: open(Z,$0);print<Z> What's the shortest pair of mutually-reproducing programs? i.e., two different programs A and B such that A produces B and B produces A. Neither A nor B should rely on hard-coded file names. -- Felix Lee flee@cs.psu.edu
merlyn@iwarp.intel.com (Randal L. Schwartz) (03/28/91)
In article <.c5G=2v91@cs.psu.edu>, flee@cs (Felix Lee) writes: | Here's a shorter non-null self-reproducing program: | | print<DATA>x 2 __END__ | print<DATA>x 2 __END__ | | And here's one shorter, but less portable: | | open(Z,$0);print<Z> Here's a short *and* portable version of that: seek(DATA,0,0);print<DATA>__END__ It even works as an arg to "perl -e"! $_ = "Just5another8Perl5hacker,"; s/(\D+)(\d)/pack("A$2",$1)/eg; print -- /=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\ | on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III | | merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn | \=Cute Quote: "Intel: putting the 'backward' in 'backward compatible'..."====/
hansm@cs.kun.nl (Hans Mulder) (03/28/91)
In article <1991Mar26.210348.12286@uvaarpa.Virginia.EDU> worley@compass.com writes: >I don't know if this has been hashed over before, but: What is the >shortest self-reproducing Perl program? (Well, the null file is, but >what is the shortest non-trivial program?) > >The best I've been able to do is: > >print @a=<DATA>,@a >__END__ >print @a=<DATA>,@a >__END__ Last time we had this debate, several shorter scripts were posted: The first example is a 3-liner; the third line being empty: print<<''x 2,$/ print<<''x 2,$/ The ohter four examples do not contain newlines; according to wc(1), they are 0-liners: This one assumes ascii, to the extent that ord("'")==39: $s='$s=%c%s%c;printf$s,39,$s,39';printf$s,39,$s,39 This one does not unduly assume anything: $_=q $_=qx;s/x/$"$_$"/;print ;s/x/$"$_$"/;print The whitespace in this one must be tabs: $_=q print"\$_=q\t$_\t;eval" ;eval This one again uses "\47" eq "'": $_='print"\$_=\47$_\47;eval"';eval Have a nice day, Hans Mulder hansm@cs.kun.nl
flee@cs.psu.edu (Felix Lee) (03/28/91)
Why does perl -e 'seek(DATA,0,0);print<DATA>__END__' emit a newline? Bonus question. Why doesn't this do the same thing? perl -e 'seek(DATA,0,0);print<DATA>^Z' where ^Z is a control-Z character -- Felix Lee flee@cs.psu.edu
jbw@bigbird.bu.edu (Joe Wells) (03/29/91)
merlyn@iwarp.intel.com (Randal L. Schwartz) writes:
seek(DATA,0,0);print<DATA>__END__
Is this guaranteed? Will Larry guarantee that DATA is always open on a
seekable file that contains the entire text of the program?
--
Joe Wells <jbw@bu.edu>lwall@jpl-devvax.jpl.nasa.gov (Larry Wall) (03/29/91)
In article <JBW.91Mar28120741@bigbird.bu.edu> jbw@bigbird.bu.edu (Joe Wells) writes: : merlyn@iwarp.intel.com (Randal L. Schwartz) writes: : : seek(DATA,0,0);print<DATA>__END__ : : Is this guaranteed? Will Larry guarantee that DATA is always open on a : seekable file that contains the entire text of the program? Nope. It doesn't work if you say echo 'seek(DATA,0,0);print<DATA>__END__' | perl However, it's guaranteed to work if the script is coming from a file. For the moment, that includes when you use -e, because it builds a temp file. Larry