XML

I've been busy and I've been on vacation so it's been awhile between posts. But I found a cool doodad that just saved my bacon so I wanted to post a link to it.

It seems that the world of XML has some very sloppy practices built into it. These are sloppy practices used by developers all around the world, including myself, and they are a recipe for disaster.

I have found in San Francisco that I simply need to visit the public library every day to get full wireless access.

As a subproject to my late but promised effort to improve the compiler for Build Your Own I am writing "yet another" XML parser. Most available parsers annoy me by exposing only a limited set of functionality.

In a corporate environment, I feel guilty about this feeling of annoyance and try to reuse, overall with less success than many .Net developers because in fact it often takes me less time to reinvent.

The parser consists of two objects, xmlParser and xmlTagInfo. xmlParser parses all the tags.

One problem I have noticed on multiple projects is that when working with the Microsoft MSXML DOM API to interact directly with an XML document you can spend a lot of time debugging failed calls to selectSingleNode(). (If I'm not mistaken, this is an extension of the standards, so the method only exists (as far as I know) in Microsoft's MSXML API.)

selectSingleNode() returns an empty object reference if the XPath does not find a match. Typically, developers will continue on past the call to selectSingleNode() without any validation of the call. If the XPath fails because of a typo or because the XML structure changed, all you get as an error is, in Visual Basic for example, an error 91, "Object variable or With block not set."