...
use overload
      "-"    => \&minus,
      "+"    => \&plus,
      "*"    => \&mult,
      "bool" => \&bool;
...
sub plus {
	my $u = shift;
	my $v = shift;
	return new Vector2D ( 
		$u->getx() + $v->getx(),
		$u->gety() + $v->gety()
	);
}
...