The difference between 

    # broomduster
    my $h = $a{$state}{$city};
    $h->{'Color'} = $color;

[download]

and 

    # ikegami
    my $r = \( $a{$state}->{$city} );
    ${ $r }->{Color} = $color;

[download]

is that only the latter autovivifies if necessary. For example, here's what happens if 

$a{'WI'}{'GreenBay'}{'Color'} = 'Black';

[download]
is commented out: 
# broomduster
$VAR1 = {
          'WI' => {}
        };

[download]
# ikegami
$VAR1 = {
          'WI' => {
                    'GreenBay' => {
                                    'Color' => 'White'
                                  }
                  }
        };

[download]

The following would also do: 

    my $h = $a{$state}{$city} ||= {};
    $h->{'Color'} = $color;

[download]

In reply to Re^3: Reference/Alias inner hash section by ikegami
in thread Reference/Alias inner hash section by mpettis

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