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xpath mess case study: .net (was: Nasty XPath expressions)

• To: Dare Obasanjo <kpako@y...>
• Subject: xpath mess case study: .net (was: Nasty XPath expressions)
• From: Christian Nentwich <c.nentwich@c...>
• Date: 14 Dec 2001 13:59:54 +0000
• Cc: xml-dev@l...
• In-reply-to: <023b01c184be$63a1df10$0500a8c0@carnage>
• References: <D7155AD41ECFD511AF4A00B0D0202CB51DFB51@MAILHOST> <1008336477.1200.3.camel@w...> <023b01c184be$63a1df10$0500a8c0@carnage>

> > I won't even start with my success of binding my own variables in the
> > .NET System.Xml classes. Their System.Xml.XPath classes do not even
> > envisage that someone might ever want to do this.. you have to pick out
> > Xsl classes, and then the exceptions start...
> If you don't mind me asking, what problems have you had?

I wrote a little test program at first: I had to subclass
System.Xml.Xsl.XsltContext, and provide my own ResolveVariable function,
which always returns the same variable.

For that purpose, I had to implement my own IXsltContextVariable class,
which returns an XmlNodeList containing one node. And in order to that,
I had to subclass XmlNodeList, because it is an abstract class, so I
cannot instantiate it, and in any case I cannot write into it.

So, I had to write 3 classes already just to set up a variable context.
But then when I call setContext with my own context on some
XPathExpression object, I get a NotSupportedException.. fanstastic :) Of
course, since it was not envisioned as a requirement, this is also not
document anywhere.

Christian Nentwich
p.s. it was just as hard with Xalan, but at least I could look into the
source code there to figure out what was going wrong.

• References:
  • RE: Nasty XPath expressions
    • From: Michael Brennan <Michael_Brennan@A...>
  • RE: Nasty XPath expressions
    • From: Christian Nentwich <c.nentwich@c...>
  • Re: Nasty XPath expressions
    • From: "Dare Obasanjo" <kpako@y...>

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