#!/usr/bin/perl
use strict;
use Data::Dumper;

my %hash1 = ( foo => my ($bar) );
$bar = 2;

my %hash2 = ( foo => \my $bar2 );
$bar2 = 2;

print Data::Dumper->Dump([\%hash1,\%hash2], [qw(*hash1 *hash2)]);