Well, you could do something along these lines:

{
my @constants = qw(scroll_x scroll_y flow_x flow_y);
sub which_constants {
  my $self = shift;
  return undef unless ref($self);
  my %hashtest;
  @hashtest{map { $_ - 1 } grep(/^\d+$/ && 0<=$_ && $_<@constants,@_)}
+ = ();
  $self->{$constants[$_]} = exists $hashtest{$_} ? 1:0 for (0..$#const
+ants);
  $self;
}
}
[download]

Of course, I'm assuming that your object is a blessed hashref. Is it pretty? Nope. But it does work and...ummm...yep. Hope this helps.

antirice    
The first rule of Perl club is - use Perl
The ith rule of Perl club is - follow rule i - 1 for i > 1