I did it this way - same effect as saurog's. I believe the problem was you were returning a copy of the array from access_cache - I just changed that to a reference and used that reference

#!/usr/bin/perl -w

use strict;
use diagnostics;

{
    my $cache = [Foo->new];
    sub access_cache {
        return \@$cache;
    }
}

foreach (@{&access_cache()}) {
    print STDERR "before: ", ref($_), "\n";
    print STDERR "object: ", $_, "\n";;
    print STDERR "after:  ", ref($_), "\n\n";
}

foreach (@{&access_cache()}) {
    print STDERR "before: ", ref($_), "\n";
    print STDERR "object: ", $_, "\n";
    print STDERR "after:  ", ref($_), "\n";
}

package Foo;
sub new {bless [], $_[0]};
use overload '""' => sub {$_[0] = Bar->new; return $_[0]->[0]};

package Bar;
sub new {bless ['barbar'], $_[0]};
use overload '""' => sub {return $_[0]->[0]};
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