Overloading: Y2K Detection Example

Program now croaks on $year % 100, $year + 1900, etc.
One solution: Just add modulus, addition, etc. methods.
Another solution:

        package y2k;
        ...
        use overload 'nomethod' => \&default;
        ...
        sub default {
          my ($y2k, $arg, $rev, $op) = @_;
          my $y = $y2k->{YEAR};
          my $expr = $rev ? "$arg $op $y" : "$y $op $arg";
          eval $expr;
        }