use warnings;
use strict;

package Soldier;

use overload '0+' => \&truncate;

my $soldier1 = {NAME   => 'BENJAMIN',
                RANK   => 'PRIVATE' ,
                SERIAL =>    151.11};

bless $soldier1;

my $int = int($soldier1);
print $int, "\n";

sub truncate {
    print "sub truncate called: ", int($_[0]->{SERIAL}), "\n";
    return int($_[0]->{SERIAL});
}

__END__

OUTPUTS:
sub truncate called: 151
sub truncate called: 151
151