#!/usr/bin/perl
use strict;
use warnings;

use Path::Class;

sub trans {
    my ($dir, $cb) = @_;

    while(my $file = $dir->next) {
        my $outfile = $file->stringify;

        # Some conditions
        next if $outfile =~ /(\.|\.\.)$/;
        next if $outfile eq $dir;

        if($file->is_dir()) {
            # make a directory
            trans($file, $cb);
            next;
        }

        $cb->($file);
    }
}

sub some {
    my ($f) = @_;

    die "f is empty" if !$f;

    print "Inside some: $f\n";
}

trans dir("in"), \&some;