use strict;
use warnings;

my $file = <<FILE;
FILE

open my $inFile, '<', \$file;
my @ids = qw(1234 2345 3456);
my %hash;

foreach my $id (@ids) {
      while (<$inFile>) {
           $hash{$id} = {
                     headline => sub { return /.*headline: (.*)/ },
                     byline => sub { return /.*byline: (.*)/},
           };
      }
      print $hash{$id}->{byline}->()."\n";
}
close $inFile;