Re: Sort alphabetically from file


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Re: Sort alphabetically from file

by tybalt89 (Prior)

on Jun 15, 2019 at 02:54 UTC ( #11101381=note: print w/replies, xml )

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in reply to Sort alphabetically from file

#!/usr/bin/perl

# https://perlmonks.org/?node_id=11101345

use strict;
use warnings;

print sort { $a =~ s/[\s\d]*//r cmp $b =~ s///r } <DATA>;

__DATA__
1  2  3  delta
1  2  3  apricot
1  2  3  charlie
1  2  3  bravo
1  2  3  echo
1  2  3  fox
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Re^2: Sort alphabetically from file
by AnomalousMonk (Bishop) on Jun 22, 2019 at 02:41 UTC

$a =~ s/[\s\d]*//r cmp $b =~ s///r

Doesn't the proper operation of the compare using this trick (for which, I think, see "The empty pattern //" in perlop) assume a left-side-then-right-side order in which cmp (see Equality Operators in perlop) evaluates its operands (which I don't see specified anywhere)? I.e.,
$a =~ s///r cmp $b =~ s/[\s\d]*//r
fails (testing under Perl version 5.14). One can imagine that such a situation might easily arise during a cut/paste change of sorting order from ascending to descending. Isn't this a bug waiting to be born (can we call it a larva)? Doesn't it at least merit a prominent comment?

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