use strict;
use File::Find;

my $cod    = shift or die 'some error message';
my $dbpath = '/path/to/somewhere';
my @files;

@ARGV = '.' unless @ARGV;

find sub {
   push(@files, $_) if /\.mp3\z/;
}, @ARGV;

open(DB, ">$dbpath/$cod.txt") || die $!;

print DB map { s/\.mp3\z/\n/; $_ } sort @files;
[download]

Looks like the original author was trying to encapsulate some functionality. I question this approach, because the subroutine indexfiles handles too many tasks and while it does accept arguments, indexfiles does not return anything and instead relies on a shared variable. (peruse the search results at google.com for tight coupling loose cohesion for some good reading.)

Like i said before, i personally prefer a script like this to be consise and without unnecessary subroutines. But, since we are on the topic, here is another version that uses two subroutines (not including the File::Find magic):

use strict;
use File::Find;

my $cod    = shift or die 'some error message';
my $dbpath = '/path/to/somewhere';

@ARGV = '.' unless @ARGV;
my @files = get_files(@ARGV);
open(DB, ">$dbpath/$cod.txt") || die $!;

print DB trim(@files);

sub get_files {
   my @file;
   find sub {
      push(@file, $_) if /\.mp3\z/;
   }, @_;
   return @file;
}

sub trim {
   return map { s/\.mp3\z/\n/; $_ } sort @_;
}
[download]

Good luck :)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)