gistfile1.txt

#!/usr/bin/perl

package Num;

use overload
    '""' => \&stringfy,
    '0+' => \&numeric;

sub new {
    my ($class, $value) = @_;
    bless \$value, $class;
}

sub stringfy {
    my $self = shift;
    qq!"$$self"!;
}

sub numeric {
    my $self = shift;
    $$self;
}

package OW;

use strict;
use warnings;
use base qw/Exporter/;
use Data::Dumper;
use Scalar::Util qw/blessed/;

our @EXPORT = qw/ow/;

use overload
    '""' => \&stringfy,
    '0+' => \&numeric;

sub ow {
    __PACKAGE__->new(shift);
}
sub new {
    my ($class, $value) = @_;
    bless \$value, $class;
}

sub stringfy {
    my $self = shift;
    my $value = $$self;
    if ( blessed($value) && (my $stringify = overload::Method( $value, '""' )) ) {
        $value = $stringify->($value);
    }
    dumper($value);
}

sub numeric {
    my $self = shift;
    my $value = $$self;
    if ( blessed($value) && (my $numeric = overload::Method( $value, '0+' )) ) {
        $value = $numeric->($value);
    }
    dumper($value);
}

sub dumper {
    my $value = shift;
    if ( defined $value && ref($value) ) {
        local $Data::Dumper::Terse = 1;
        local $Data::Dumper::Indent = 0; 
        $value = Data::Dumper::Dumper($value);
    }
    $value;
}

1;

package main;

use URI;
use Scalar::Util qw/dualvar/;

my $uri = URI->new("http://yahoo.co.jp");;
printf "1: %s\n", OW::ow($uri);
printf "2: %d\n", OW::ow($uri);
printf "3: %f\n", OW::ow($uri);
printf "4: %o\n", OW::ow($uri);

my $num = Num->new(200);
printf "1: %s\n", OW::ow($num);
printf "2: %d\n", OW::ow($num);
printf "3: %f\n", OW::ow($num);
printf "4: %x\n", OW::ow($num);