This is the weirdest bug and I'm totally confused.

I created a buggy function but my tests miraculously passed none the less.

I narrowed it down to this demo where sort is magically expanding stringified hashrefs like "HASH(0x253f0c8)" ...

(see <--- WTF? in output)

Could someone please explain the difference between sort AoH and sort {$a cmp $b } AoH here

use v5.12;
use warnings;
use Data::Dump;


my $AoH;

debug_loop_join();exit;

sub loop_join {
    my %H;
    $H{$_} = ()  for @$AoH;
    return keys %H;
}
sub debug_loop_join {
    $AoH = create_data (.2, 10);
    ddx [ loop_join  ($AoH) ];
    ddx [ sort  loop_join  ($AoH) ];
    ddx [ sort {$a cmp $b } loop_join  ($AoH) ];
}


sub create_data {
    my ($density, $records) = @_;

    my @AoH;
    push @AoH, {map { rand 100 <= $density ? ( $_ => $_ ) : () } "A" .
+. "ZZ"}
        for 1 .. $records;
    return \@AoH;
}

[download]
OUTPUT: 
# sort_hash_bug.pl:18: [
#   "HASH(0x253f0c8)",
#   "HASH(0x25350c8)",
#   "HASH(0x268aa20)",
#   "HASH(0xeea828)",
#   "HASH(0x2535548)",
#   "HASH(0x2535128)",
#   "HASH(0x268aab0)",
#   "HASH(0x2535260)",
#   "HASH(0x268a840)",
#   "HASH(0x268a918)",
# ]
# sort_hash_bug.pl:19: [                                       # <--- 
+WTF?
#   [
#     {},
#     { AZ => "AZ", EM => "EM", RY => "RY" },
#     {},
#     { GT => "GT", JR => "JR", RZ => "RZ" },
#     { HY => "HY" },
#     { HT => "HT" },
#     { VH => "VH", WU => "WU" },
#     { GR => "GR", HH => "HH", HM => "HM", JC => "JC", WJ => "WJ" },
#     {},
#     { BK => "BK", UH => "UH", XX => "XX", ZN => "ZN" },
#   ],
# ]
# sort_hash_bug.pl:20: [
#   "HASH(0x25350c8)",
#   "HASH(0x2535128)",
#   "HASH(0x2535260)",
#   "HASH(0x2535548)",
#   "HASH(0x253f0c8)",
#   "HASH(0x268a840)",
#   "HASH(0x268a918)",
#   "HASH(0x268aa20)",
#   "HASH(0x268aab0)",
#   "HASH(0xeea828)",
# ]

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to sort AoH buggy? by LanX

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