Inplace edit using XML::Twig

GrandFather has asked for the wisdom of the Perl Monks concerning the following question:

Is there a way to inplace edit using XML::Twig, or have I got to go through the pain of creating a temporary file and replacing the original? Is there a better way to do that than the following?

    # Edit the manifest
    my $saveStdOut = select;
    my $manifestOut;
    open $manifestOut, '>', "$manifestPath.new";
    select $manifestOut;

    $sub = bindArgs (\&insertFiles, $absDir, \@fileList);
    my $twig = XML::Twig->new (
        discard_spaces => 1,
        pretty_print => 'indented',
        twig_roots => {'sourceFiles' => $sub,}, # Insert file list
        twig_print_outside_roots => 1, # Print the rest
        );
    
    $twig->parsefile ($manifestPath);
    select $saveStdOut;
    close $manifestOut;
    
    unlink $manifestPath;
    rename $manifestPath . '.new', $manifestPath;
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Comment on Inplace edit using XML::Twig Download Code

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Re: Inplace edit using XML::Twig by mirod (Canon) on May 22, 2006 at 10:02 UTC
If you grab the development version of XML::Twig at the usual place, then you should have a look at the `parsefile_inplace` method. Does it help?	[reply]
Re^2: Inplace edit using XML::Twig by aufflick (Deacon) on May 23, 2006 at 08:05 UTC
Life would be so much harder without XML::Twig - nice one!	[reply]
Re: Inplace edit using XML::Twig by kvale (Monsignor) on May 22, 2006 at 03:40 UTC
Why not just read in the file contents, truncate the file, and write processed file contents back out to the same file? No delete and rename needed. -Mark	[reply]
Re^2: Inplace edit using XML::Twig by gellyfish (Monsignor) on May 22, 2006 at 08:34 UTC
There are two reasons, firstly renaming is an atomic operation on all the systems that I am aware of so there is no risk of another application that can't be made to co-operate with this one getting a partially written file, secondly writing to a second file mitigates against the risk of the file being corrupted if the process is interrupted due to a program or OS crash or hardware failure for instance. For the most part I would omit the deletion stage to further reduce the risk of losing the file (although some OS might not support this). /J\	[reply]
Re^2: Inplace edit using XML::Twig by greenFox (Vicar) on May 22, 2006 at 08:07 UTC
Tim Bray makes some suggestions why you might not want to do that here, the caveat being of course how important is the data in question. -- Do not seek to follow in the footsteps of the wise. Seek what they sought. -Basho	[reply]