package Calc::Euro;
use strict;
use Carp;
my %rates = qw(
        LUF 40.3399     ATS 13.7603     BEF 40.3399
        NLG 2.20371     FIM 5.94573     FRF 6.55957
        DEM 1.95583     GRD 340.75      IEP 0.787564
        ITL 1936.27     PTE 200.482     ESP 166.386 
);

sub new {
    my ($proto, $currency) = @_;
    my $rate = defined $currency && (
                   $rates{uc $currency} || 0 + $currency
               ) ||
               ( ref $proto eq __PACKAGE__ ?
                   $$proto
               :
                   croak("Invalid currency")
               );
    return bless \$rate, ref($proto) || $proto;
}

sub to_euro {
    my ($self, $amount) = @_;
    return $amount / $$self;
}

sub to_national {
    my ($self, $amount) = @_;
    return $amount * $$self;
}

sub from_euro     { goto &to_national }
sub from_national { goto &to_euro }
sub clone         { goto &new }