That said, I do agree delimited files can make a lot of sense for lightweight data storage. For information that normally wouldn't contain internal whitespace other than "regular" (ASCII 32) spaces -- and this application might qualify -- I often choose tab-delimited.

One potential benefit I do see to using XML in this application is that you can easily store data that isn't quite so regular. For example, if you wanted to support multiple contact phone numbers, it would be fairly easy to expand the data structure like this:

<record>
<!--existing stuff-->
<contact_phone_number note="business">123-4567</contact_phone_number>
<contact_phone_number note="pager">555-6789</contact_phone_number>
<contact_phone_number note="vacation home in Bermuda">+1-99-20-55-6789
+</contact_phone_number>
</record>
[download]

Dealing with irregularities like that would be a bit more work in a rigid db-like or non-hierarchical file format.

        $perlmonks{seattlejohn} = 'John Clyman';

I entirely agree with your comments and that is why DBD::CSV has all the usual parameters for setting the "elastic" properties of CSV.

Of course XML cannot be beaten for storage of irregular records. Anyone would be hard pressed to equal such a flexible system for irregular data and still maintain a sense or order.

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law

There's an anti-buzzword backlash against XML floating around, which is a natural reaction to something that's been hyped so much by marketers.

But after all the smoke clears, it's pretty hard to beat the simplicity of using XML::Simple's XMLin() and XMLout() functions.

CSV files combined with while (<IN>) {...} logic has old-school appeal, but in the end, it's irritating and tedious. There's so many exceptions to be handled, like data that splits over lines, or data that contains the delimiter as part of the data, etc, and it's not as flexible as XML when you have to add new variables.

Don't get me wrong: There are lots and lots of things that are appealing about XML; I've used it numerous times to develop production apps, including tools that have to munge XML documents hundreds of thousands of lines long. And I love XML::Simple, because it makes using XML almost as easy as using native Perl data structures via something like Data::Dumper.

At the same time, though, I think it can be worth pointing out that, like any technology, XML is not necessarily the ideal solution for every problem. XML doesn't permit random access to records (though neither does CSV), it tends to be verbose, and you have to be careful with your document structure. XML::Simple hides most of that tedium, but then the various CSV modules on CPAN also take care of a lot of that for CSV as well.

        $perlmonks{seattlejohn} = 'John Clyman';