use strict;
my $file = shift @ARGV;
open (INPUT, "<$file");
my @ids = qw(1234 2345 3456);
my %hash;

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