use warnings;
use strict;
use Foo;
use Bar;

my $foo = new Foo;
my $bar = new Bar($foo);

$foo->x("from program");
print "(app) Memory: $foo, X: ".$foo->x()."\n";
$bar->show();

##</code><code>##

package Foo;

sub new {
    my $name = shift;
    bless { x => 'from Foo' }, $name;
}

sub x {
    my ($self, $arg) = @_;
    $$self{x} = $arg if ($arg);
    return $$self{x};
}

1;


##</code><code>##

package Bar;

sub new {
    my $name = shift;
    my $foo = shift;

    bless { foo => $foo }, $name;
}

sub show {
    my $self = shift;
    my $foo = $$self{foo};
    print "(bar) Memory: $foo, X: ".$foo->x()."\n";
}

1;