use IO::File;

sub process_each_file_line
{
  my( $filename, $preprocess_cb, $process_cb ) = @_;
  my $fh = IO::File->new( "< $filename" ) 
    or die "open $filename for reading: $!";
  while ( <$fh> )
  {
    $process_cb->( $preprocess_cb->() );
  }
}

sub make_file_processor
{
  my( $filename, @indexes ) = @_;
  return sub {  # make a closure which takes no args.
    my @result;
    process_each_file_line(
      $filename,
      sub { (split)[ @indexes ] },
      sub { local $" = ','; push @result, "test : @_\n"; }
    );
    return @result;
  }
}

# create the processor for the given input params:
my $processor = make_file_processor( "my.dat", qw( 3 0 4 5 6  7 ) );

# later on, call the closure:
print $processor->();