use Symbol;
{
  my @indexes = qw (3 0 4 5 6 7);
  my $fh = gensym;
  open $fh,"<my.dat" or die "my.dat: $!";
  sub read_row {
   my $row = <$fh>;
   close $fh and return unless defined($row);
   return (split(/\s+/,$row))[@indexes];
  }
}