#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

package HexNumber;

use Moose;
use overload    '+'     => \&add,
                '""'    => \&to_s;

has '_value'     =>  ( is => 'rw' );

sub set {
    my $self = shift;
    my $val = shift;
    return unless $val =~ /^[\da-fA-F]+$/;
    $self->_value(hex($val));
}

sub add {
    my $self = shift;
    my $other = shift;
    return (blessed $other) ?
        HexNumber->new(_value => $other->_value + $self->_value) :
        HexNumber->new(_value => $other + $self->_value) ;
}

sub to_s {
    my $self = shift;
    return sprintf '%x', $self->_value;
}

package main;

sub to ($) { shift } # just syntactic sugar

my $foo = HexNumber->new(_value => '44800'); # only dec-values directly
my $bar = HexNumber->new();

set $bar to 'fe'; # the same as $bar->set('fe');

my $buz = $foo + $bar;
print $buz, "\n" x 2;
print Dumper \$buz;