Saturday I Get to Rant (XML Config Edition)

After writing a little bit about django's settings file not being in XML I'm left with half a rant ready to go and I've done enough for this week so I get to let it out.

I've been exposed to that complicated XML config file world back in Java land. I don't mind the Java language (except for generics, but that's another rant) but it has some very, very stupid friends.

A lot of the time creeping XML seems to come from a deep seated desire to create behavior that doesn't have to be programmed. Configuring somehow doesn't count as programming, even when it's thousands of lines. Which is good, because XML doesn't count as a programming language. Unfortunately the first statement there is just wishful thinking: complex system configuration is so close to programming that they're wearing the same pants. And doing a programming task in XML is like knitting with mittens on.

And of course it comes with a bunch of other problems, like separating pieces of object behavior so you can't learn both what fields it has and how it behaves without finding both the code and the magic XML section. Separating pieces of object behavior into different files drives me up two walls at once.

Finally, each XML config file format is effectively a miniature programming language designed by someone who didn't know they were designing one, with predictably wonderful results.

XML config defenders will talk about how you can validate the config file with a DTD or schema or whatever, but this is a big glass of snake oil. Sure, you can validate the format of the config file, and field values, but as soon as one field relates to another you're going to have to validate it with real code anyway. XML defenders might also talk about how XML is human readable. I'm not sure what the proper response to those people is. Probably we should make them sing their own config files - if you can read it, shouldn't you be able to sing it?

Anyway django configuration is just about my style. Generally items are just named values, or lists of values, and on the outside chance you need something more complicated, you can unleash a real programming language.

There's another related rant for another time about the whole XML web hellworld that is the WS* specifications for SOAP and associated perversions, but I should limit myself to one per week.