Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Randal's one-liners
Message-ID: <7349@jpl-devvax.JPL.NASA.GOV>
Date: 8 Mar 90 23:48:18 GMT
References: <15214@bfmny0.UU.NET> <15216@bfmny0.UU.NET> <7250@jpl-devvax.JPL.NASA.GOV> <E4uj=r1@cs.psu.edu> <7282@jpl-devvax.JPL.NASA.GOV> <1990Mar6.110732.11660@kaukau.comp.vuw.ac.nz>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 28

In article <1990Mar6.110732.11660@kaukau.comp.vuw.ac.nz> ajv@comp.vuw.ac.nz (Andrew Vignaux) writes:
: I'm afraid I can't get my submission down to 1 line (excluding data) :-(
: Can anyone help?
: 
: @l = split (/(..)/,'1a7r4J1n0a7e7c1o8n248o1t4u8v4s7.207l27547a7n7g1h'.
: '0 511e3h7.8i564t3a6P1r7p8c8e6e3c3k7e3e533r7r286r6l4 6 1 8,7l7 3,');
: srand; $_=3*int(rand(2))+2; /^$_/;
: foreach (split(//,&g)) {/^$_/;print &g;} print "\n";
: sub g {join('',grep(s/^.//,grep(//,@l)));}

You want it in one line?  Does it have to fit in 80 columns?   :-)

I really liked your "holographic" approach.  I had to stare at it quite
some time for things to resolve.  I thought I was going crazy when it
printed out something different when I ran it on a different machine.

: The interesting bit is the "grep(//,@l)".  Is this a "feature" ;-)
: Can anyone exploit it in a real script?

Yes, it's a feature.  Any null pattern (except in a split) just refers
back to the last real pattern match, ala ed and sed.

I imagine this would be one mechanism for getting around the problem
mentioned earlier of having run-time patterns that you don't want to
recompile every iteration of a grep, but that you want to change
occasionally, which rules out /$pat/o (except in an eval).

Larry