Re: Calculations with formatted numbers

Here is the "magic" answer:

package Number::Formatted;
use Number::Format;
my $format = new Number::Format (
    thousands_sep => '.',
    decimal_point => ',' );
use overload
    '""' => sub { $format->format_number( ${$_[0]} ) },
    '+' =>  sub { 
        my $num = ref( $_[1] ) ? ${$_[1]} : $_[1];
        $num = ${$_[0]} + $num;
        return bless \$num, Number::Formatted;
    },
    fallback => 1;
sub new { 
    my $num = $format->unformat_number( $_[1] );
    return bless \$num, $_[0];
}

package main;

my $n = new Number::Formatted ( '1.234,56' );
my $m = new Number::Formatted ( '123,45' );

print $n, "\n";
print $n + 10, "\n";
print $n + $m, "\n";

# 1.234,56
# 1.244,56
# 1.358,01
[download]

Comment on Re: Calculations with formatted numbers Download Code

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Re^2: Calculations with formatted numbers by holli (Abbot) on Feb 16, 2005 at 10:17 UTC
Thank you! Exactly what i was looking for! So i created similar overloads for the other operators (-, , /, ) that work fine. But these do not: `#... '++' => sub { $num = ${$_[0]} + 1; return bless \$num, Number::Formatted; }, '--' => sub { $num = ${$_[0]} - 1; return bless \$num, Number::Formatted; },` [download] Any idea why? holli, /regexed monk/*	[reply] [d/l]
Re^3: Calculations with formatted numbers by fglock (Vicar) on Feb 16, 2005 at 12:40 UTC
++ and -- are mutators - see perldoc overload. This is how to implement them: package Number::Formatted; use Number::Format; my $format = new Number::Format ( thousands_sep => '.', decimal_point => ',' ); use overload '""' => sub { $format->format_number( ${$_[0]} ) }, '+' => sub { my $num = ref( $_[1] ) ? ${$_[1]} : $_[1]; $num = ${$_[0]} + $num; $num = - $num if $_[2]; return bless \$num, Number::Formatted; }, '-' => sub { my $num = ref( $_[1] ) ? ${$_[1]} : $_[1]; $num = ${$_[0]} - $num; $num = - $num if $_[2]; return bless \$num, Number::Formatted; }, '++' => sub { ++ ${$_[0]}; shift }, '--' => sub { -- ${$_[0]}; shift }, ; sub new { my $num = $format->unformat_number( $_[1] ); return bless \$num, $_[0]; } package main; my $n = new Number::Formatted ( '1.234,56' ); my $m = new Number::Formatted ( '123,45' ); print $n, "\n"; print $n + 10, "\n"; print $n + $m, "\n"; print $n - $m, "\n"; print ++$n, "\n"; # 1.234,56 # 1.244,56 # 1.358,01 # 1.111,11 # 1.235,56 [download]	[reply] [d/l]