The issue is that the original line ends are retained, but that new lines are expanded to OS specific line endings. One work around for modest size files is to slurp the file then use parse.

This code demonstrates the parsing problem:

use warnings;
use strict;
use XML::Twig;

my $str = <<"XML";
<?xml version="1.0" encoding="utf-8"?>\r
<experiment title="Blood Pressure" version="1.2" softwareVersion="1.1"
+>\r
<sourceFiles>\r
</sourceFiles>\r
<dataFiles>\r
<dataFile>cuff practice.dat</dataFile>\r
</dataFiles>\r
</experiment>\r
XML

# Troublesome code
print "******* Troublesome version\n";
my @fileList = qw(first second);
my $sub = bindArgs (\&insertFiles, \@fileList);
my $twig = XML::Twig->new (
    twig_roots => {'sourceFiles' => $sub,}, # Insert file list
    twig_print_outside_roots => 1, # Print the rest
    );

$twig->parse ($str);


sub bindArgs {
  my ($sub, @args) = @_;
  return sub {$sub->(@args, @_);};
}


sub insertFiles {
    my ($sourceFiles, $twig, $node) = @_;
   
    for (@$sourceFiles) {
        my $eFile = $twig->root->new (sourcefile => $_); # create the 
+element
        $eFile->paste (first_child => $node);
    }
    $node->print ();
}
[download]

Prints:

******* Troublesome version
<?xml version="1.0" encoding="utf-8"?>

<experiment title="Blood Pressure" version="1.2" softwareVersion="1.1"
+>

<sourceFiles><sourcefile>second</sourcefile><sourcefile>first</sourcef
+ile></sourceFiles>

<dataFiles>

<dataFile>cuff practice.dat</dataFile>

</dataFiles>

</experiment>
[download]

It would be nice if XML::Twig or XML::Parser collapsed various line ending sequences to a single \n character or alternatively XML::Twig should ignore non-signficant line endings.

Yes I still have the problem that the output generated by twig_print_outside_roots (that is, the original XML) is generated with line endings as "\r\r\n" rather than the "\r\n" line endings that are conventional for windows.

I would guess that the parser is striping "\n" characters rather than $/, but that print is generating OS specific line endings. Given that *nix uses "\n" line endings it is unsurprising that the sample code produces correct output on a *nix system.

The problem remains, although I now understand why it is there somewhat. I still don't know how to fix it within XML::Twig.

You seem be under the mistaken impression that $/ is different on Windows than it is elsewhere. $/ is just "\n" (by default) everywhere.

This problem would happen on Windows if the input is read in binmode but the output is written without binmode.

- tye