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

use Text::CSV_XS;
use XML::Twig;

my $twig = 'XML::Twig'->new(...);
my $csv  = 'Text::CSV_XS'->new(...);

my $listfile = shift;
open my $list, '<', $listfile or die $!;
while (my $xmlfile = <$list>) {
    chomp $xmlfile;
    $twig->parsefile($xmlfile);
    ...
}