use strict; 
use warnings;

use File::Glob qw( bsd_glob );

sub search_files {
   my ($re, @files) = @_;

   my $fh;
   my $file_name;

   return sub {
      START:

      if (not defined $file_name) {
         return () if not @files;
         $file_name = shift(@files);

         if (!open($fh, '<', $file_name)) {
            warn("Unable to open file \"$file_name\": $!\n");
            undef $file_name;
            goto START;
         }
      }

      while (defined(my $line = <$fh>)) {
         if ($line =~ /$re/) {
            return ( $file_name, $., $line );
         }
      }

      undef $fh;
      undef $file_name;
      goto START;
   };
}

{
   my @files = bsd_glob('*');
   my $re    = qr/^source*/;

   my $iter = search_files($re, @files);

   while (my ($file_name, $line_num, $line) = $iter->()) {
      print("$file_name,$line_num: $line");
   }
}