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

my $username        = "PerlMonk";
my $password        = "VeryGoodPassword";
my @email_addresses = ( "Monk1", "Monk2", "Monk3" );

my %Record1 = ( 
                  username        => $username,
                  password        => $password, 
                  emailAddress    => [@email_addresses]
               );
               
my %Record2 = (
                  username        => 'SomeOtherPerlMonk',
                  password        => 'AntoherVeryGoodPassword', 
                  emailAddress    => ["monka", "monkb", "monkc"],
               );
               
my @AoH;
push (@AoH, {%Record1}); #{%Record1} allocates new memory
                         #for the anonymous hash, makes a copy,
                         #of the whole hash table, then adds a 
                         #reference to that anon hash
                         #to the array @AoH (similar to a C pointer).
push (@AoH, {%Record2});

print Dumper \@AoH;

$username = "XXXXXXXXXXXXXXXXXXXX";

# the record in AoH is unchanged because $username was copied
# into that record

#print Dumper \@AoH; #un-coment to see same thing again

print "\nDumping records....\n";

foreach my $record (@AoH)
{
   foreach my $key (keys %$record)
   {
       if ( ref ($record->{$key}) eq 'ARRAY'  )
       {
           print "$key => @{$record->{$key}}\n";
       }
       else
       {
          print "$key => $record->{$key}\n";
       }
   }
   print "\n";
}
__END__
$VAR1 = [
          {
            'password' => 'VeryGoodPassword',
            'emailAddress' => [
                                'Monk1',
                                'Monk2',
                                'Monk3'
                              ],
            'username' => 'PerlMonk'
          },
          {
            'password' => 'AntoherVeryGoodPassword',
            'emailAddress' => [
                                'monka',
                                'monkb',
                                'monkc'
                              ],
            'username' => 'SomeOtherPerlMonk'
          }
        ];

Dumping records....
password => VeryGoodPassword
emailAddress => Monk1 Monk2 Monk3
username => PerlMonk

password => AntoherVeryGoodPassword
emailAddress => monka monkb monkc
username => SomeOtherPerlMonk