Based on your idea, I made my own Perl Eurocalculator with the following changes:

1. Has a cloneable object-oriented interface
2. The euro is a currency too, so toCurrency isn't really clear => uses to_national
3. Includes the Luxembourgian Franc (there are _12_ euro countries)
4. Uses the official three-letter abbreviations
5. Can handle user-defined rates
6. Has both from_euro and to_national
7. Update (200201021239+0100) Corrected wrong values: DEM (typo), FIM (typo), ATS

Without further ado, here's the module:

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 }
[download]

And of course a script to prove it works ;)

#!/usr/bin/perl -w

use strict;
use Calc::Euro;

my $eurocalc = Calc::Euro->new('NLG');
print $eurocalc->to_national(1), "\n"; # 2.20371

my $anothercalc = $eurocalc->clone();
print $eurocalc->to_national(1), "\n"; # 2.20371

$eurocalc = Calc::Euro->new('BEF');
print $anothercalc->from_euro($eurocalc->to_euro(20)), "\n";
# approx 1

my $foo = Calc::Euro->new(1.5);
print $foo->to_national(2), "\n"; # 3
[download]

Have fun!

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
[download]

for the sake of simplicity, how about adding a EUR => 1 in the hash and getting rid of the National vs Euro distinction :)

eurCalc($value, $from, $to)

Tiago

Well in the spirit of that request, heres an additional sub which you can add to the module. You must add the additional key value pair of 'EUR' => 1 to the rates hash or you'll have problems doing any euro conversions :)



sub euroCalc
{
    my ($self,$amount, $from,$to) = @_;
    croak("Invalid start currency") unless defined($rates{uc $from});
    croak("Invalid target currency") unless defined($rates{uc $to});
    
    # What was it in Euros
    # $amount = ($amount * $rates{$to}) / $rates{$from};
    # Now convert to target currency
    # return $amount * $rates{$to};
    
    # Or in one line
    return ($amount * $rates{$to}) / $rates{$from};
}
[download]



And some test prints



use strict;
use Calc::Euro;

my $eurocalc = Calc::Euro->new('NLG');
print $eurocalc->to_national(1), "\n"; # 2.20371

print $eurocalc->euroCalc($eurocalc->euroCalc(1,'NLG','EUR'),'EUR','NL
+G'), "\n"; 
print $eurocalc->euroCalc(1,'NLG','BEF'), "\n"; 
print $eurocalc->euroCalc(1,'NLG','EUR'), "\n";
print $eurocalc->euroCalc(1,'EUR','NLG'), "\n";
[download]



So you notice that you can go from one currency to Euros and then to your target currency. Might prove handy to someone.

Have fun :)

The exchange rates from the old currencies to the Euro are now immutable so we can code the rates into our scripts directly - if a rate does change its likely that it would hit the news first.

Actually, the exchange rates have been immutable since Jan 1st 1999. I was writing Euro conversion programs with hard-coded values when the Euro was first introduced three years ago.

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg

That seems like a poor way to do it (having the rate be immutable for 2 years, that is). What is to keep a country from plunging its currency straight in to the toilet (accidentally or otherwise) only to have the exchange rate be the same as when their currency was strong? Things that make you go hmmmm...

thor

What actually happened was that on Jan 1st 1999, the Franc, the Mark, the Lira and the other nine currencies all ceased to exist in any real sense. At that point, the exchange rates to the Euro were fixed. All financial dealings in these currencies became dealings in the Euro. Euros were only converted to the old national currencies when you wanted physical coins and notes in your pocket. All the fuss in the news over the last few days was, in some ways, deceptive. The 12 countries have been using the Euro for three years now. The only difference this year is that notes and coins have been issued.

--
<http://www.dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg

--
paco for president
TomK32 - just a geek trying to change the world

Um, no, the whole table is in English. Hence, it's "German mark" and "Italian lira", not "Deutsche Mark" and "Lira Italiano".

I thought Deutche Mark.

But still, three-letter ISO (DEM for DEutsche Mark) codes would be better.

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
[download]

ISO 4217 if anyone is interested.