DoubleLinkedListElement.pm:
package DoubleLinkedListElement;

use Hash::Util (lock_keys);

use strict;

sub new {
    my $self = {};
    $self->{VALUE} = undef;
    $self->{NEXT} = undef;
    $self->{PREV} = undef;
    bless $self;
    lock_keys(%$self);
    return $self;
}

sub value {
    my $self = shift;
    if (@_) {
        $self->{VALUE} = shift;
    }
    return $self->{VALUE};
}

sub next {
    my $self = shift;
    my $ret = $self->{NEXT};
    if (@_) {
        $self->{NEXT} = shift;
    }
    return $ret;
}

sub prev {
    my $self = shift;
    my $ret = $self->{PREV};
    if (@_) {
        $self->{PREV} = shift;
    }
    return $ret;
}

1;
        
DoubleLinkedList.pm:
package DoubleLinkedList;

use DoubleLinkedListElement;
use Hash::Util (lock_keys);

use strict;

sub new {
    my $self = {};
    $self->{FIRST} = undef;
    $self->{LAST} = undef;
    bless $self;
    lock_keys(%$self);
    return $self;
}

sub first {
    my $self = shift;
    return $self->{FIRST};
}

sub last {
    my $self = shift;
    return $self->{LAST};
}

sub append {
    my ($self, $value) = @_;
    my $element = new DoubleLinkedListElement();
    $element->value($value);
    if ($self->last()) {
        $self->last()->next($element);
        $element->prev($self->last());
        $self->{LAST} = $element;
    } else {
        $self->{FIRST} = $element;
        $self->{LAST} = $element;
    }
}

sub process_thru_forward {
    my ($self, $func, @param) = @_;
    for (my $this = $self->first(); $this; $this = $this->next()) {
        &$func($this, @param);
    }
}

sub process_thru_backward {
    my ($self, $func, @param) = @_;
    for (my $this = $self->last(); $this; $this = $this->prev()) {
        &$func($this, @param);
    }
}

1;
        
test.pl:
use Data::Dumper;
use DoubleLinkedList;

use strict;

my $dl_list = new DoubleLinkedList;
foreach (1..10) {
    $dl_list->append($_);
}

$dl_list->process_thru_forward(\&plus_and_display, 10);
$dl_list->process_thru_backward(\&plus_and_display, 10);

sub plus_and_display {
    my ($this, $adj) = @_;
    print $this->value + $adj, "\n";
}