I'm using this code to delete nodes from a file 
 
my $parser = XML::LibXML->new();
$dom = $parser->parse_file( "OLDFILE" );

for my $matrix ( $dom->findnodes( q{  //version_matrix/vm[@type='br'] 
+ } )) {
    my $version = $matrix->findvalue('./release/@version');
    if( $version gt $brver ) { 
        print "discarding version_matrix for $version\n";
        my $version_matrix_node = $matrix->parentNode;
        $version_matrix_node->unbindNode;
    }
}
my $changed = $dom->toString;
my $fh;
open( $fh, '>', "NEWFILE" );
print { $fh }  $changed;

[download]
where the input "OLDFILE" data is like this fragment: 
<supported_version_matrix>
    <version_matrix>
        <app>
            <release version="10.1.e">
                <fixed>125.2004</fixed>
            </release>
        </app>
        <vm type="br">
            <release version="7.3.0">
            </release>
        </vm>
    </version_matrix>
    <version_matrix>
        <app>
            <release version="10.1.e">
                <fixed>125.2004</fixed>
            </release>
        </app>
        <vm type="br">
            <release version="7.2.2">
            </release>
        </vm>
    </version_matrix>
    . . .
</supported_version_matrix>

[download]
The output file "NEWFILE" has gaps of a couple of lines in place of the discarded nodes, like this (where the version_matrix for br 7.3.0 was unbound): 
<supported_version_matrix>


    <version_matrix>
        <app>
            <release version="10.1.e">
                <fixed>125.2002</fixed>
            </release>
        </app>

[download]
The blank lines in the gaps each contain a couple of tab characters only. I think (but not 100% sure) that from an xml perspective this doesn't change the structure, but it looks bad. Am I doing something wrong, like maybe the "$matrix" child node has to be freed somehow before its parent can be unbound? Or is there an easy way to avoid it?

thanks for any illumination

In reply to XML::LibXML unbindNode leaves blank lines in the xml file by anadem

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