# a lvalue subroutine can be assigned to
# so, one could roll one's own vec, for example.
# following is only a simple demo, though

$a;
$b;

sub test : lvalue
{
	my $cond = shift;
	$cond ? $a : $b; # assign to a or b
}

sub printthem 
{
	$a = "undef" unless $a;
	$b = "undef" unless $b;
	print "a is $a and b is $b\n";
}

# lvalue subroutine 
test(0) = 1; # assign to $b
printthem();
$a = $b = undef;
test(1) = 1; # assign to $a
printthem();