38_collection.pl

package MultipleFileUploader;
use Moose::Role;

requires 'upload_file';

sub upload_files {
    my $self = shift;

    my @success;

    foreach my $f ( @_ ) {
        die "Invalid file: $f" if ! $f->DOES('File');
        $self->upload_file ( $f ) && push @success, $f;
    }

    return @success;
}

package FTPFileUploader;
use Moose;

with 'MultipleFileUploader';

sub upload_file { ... }