#!/usr/perl/bin/perl -w
use strict;
my @indexes = qw (3 0 4 5 6 7);
open INDATA,"<my.dat" or die "my.dat: $!";
sub read_row {
   my $row = <INDATA>;
   return unless defined($row);
   return (split(/\s+/,$row))[@indexes];
}
test::process(\&read_row);
close INDATA;

package test;
sub process {
   my $callback = shift;
   while (my @row = &$callback) {
      print "test : " . join(",",@row) . "\n";
   }
}
1;