http://qs321.pair.com?node_id=11101381


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

Replies are listed 'Best First'.
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?


    Give a man a fish:  <%-{-{-{-<