I haven't had a call to use one of the Cache modules yet, but I would try something like this:

#!/usr/bin/perl

use strict;
use warnings;
use Cache::MemoryBackend;
use Data::Dumper::Concise;

my $backend = new Cache::MemoryBackend(
    '/root/Desktop/tmp/FileCache', 2, 000);
$backend->store( 'Animal', 'dog' );
$backend->store( 'Animal', 'raccoon');
print Dumper($backend->get_keys('Animal'));
[download]