Note that:

    my $s = ();

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is equivelent to

    my $s = (undef);

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which is equivelent to:

    my $s;

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The first use of a hash ref autovivifies the referred hash making the previous assignment redundant (and misleading). Consider:

use strict;
use warnings;
use Data::Dump::Streamer;

my $s = ();
Dump ($s);
$s->{'a'} = 10 ;
Dump ($s);

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which prints:

$VAR1 = undef;
$HASH1 = { a => 10 };

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and note that the contents of $s changes from an undefined value to a hash ref.

If you really want to indicate intent with an assignment use:

    my $s = {};

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DWIM is Perl's answer to Gödel

In reply to Re^2: hash from sub directly into foreach loop by GrandFather
in thread hash from sub directly into foreach loop by jeanluca

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