Hi Monks,

to use a constant defined constant as a hash key it is a common notation to write $hash{+CONST}. But why does it not work if I use the '+' notation to literally specify a hash? Example:

use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Sortkeys = 1;

use constant FOO => 'the FOO key';

my %h1 = ( +FOO  => "the value" , FOO_const => FOO);
my %h2 = ( FOO , "the value",  FOO => "other value");  # comma
my @a  = ( +FOO, FOO);

print(Dumper(\%h1, \%h2, \@a), $h2{+FOO}, "\n");

[download]
This prints: 
$VAR1 = {
          'FOO' => 'the value',
          'FOO_const' => 'the FOO key'
        };
$VAR2 = {
          'FOO' => 'other value',
          'the FOO key' => 'the value'
        };
$VAR3 = [
          'the FOO key',
          'the FOO key'
        ];
the value

[download]
Surprisingly, the +FOO in the initialization of %h1 is turned to the string 'FOO'. Yes, i can use the standard comma or (FOO) =>... instead, but i would like to understand why the '+' notation does not work as expected when used left to a fat comma.

In reply to Why is +CONST left to a fat comma not treated as in $hash{+CONST}? by Darkwing

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