my $x = 4;
my $xx = sub{\@_}->(\$x, \$x);
my $y = \4;
my $yy = sub{\@_}->($y, $y);

bless \$xx->[0], 'Foo';
bless \$xx->[1], 'Bar';
bless \$yy->[0], 'Foo';
bless \$yy->[1], 'Bar';

use Data::XDumper qw(Dump);
print "******** Data::XDumper ********\n";
Dump $xx, $yy;
print "\n";

use Data::Dumper;
print "******** Data::Dumper ********\n";
print Dumper $xx, $yy;
print "\n";

use Data::Denter;
print "******** Data::Denter ********\n";
print Denter $xx, $yy;
print "\n";

# (by merlyn's suggestion in the reply)
$Data::Dumper::Purity = 1;
print "******** Data::Dumper with purity ********\n";
print Dumper $xx, $yy;
print "\n";

# and also
use YAML ();
print "******** YAML ********\n";
print YAML::Dump $xx, $yy;
print "\n";

##</code><code>##

******** Data::XDumper ********
        [
           Foo \
$L002:        4,
           Bar \$L002
        ]
        [
$L001:     Bar \<ro> 4,
           $L001
        ]

******** Data::Dumper ********
$VAR1 = [
          \4,
          $VAR1->[0]
        ];
$VAR2 = [
          \4,
          $VAR2->[0]
        ];

******** Data::Denter ********
@
    $(REF00001)
        4
    $(*REF00001-1)
@
    $(REF00002)
        4
    $(*REF00002-1)

******** Data::Dumper with purity ********
$VAR1 = [
          \4,
          do{my $o}
        ];
$VAR1->[1] = $VAR1->[0];
$VAR2 = [
          \4,
          do{my $o}
        ];
$VAR2->[1] = $VAR2->[0];

******** YAML ********
--- #YAML:1.0
- &1 !perl/ref:
  =: 4
- *1
--- #YAML:1.0
- &1 !perl/ref:
  =: 4
- *1