[Exist-development] Pushing error message xquery line numbers into type comparisons

[Adam R. <ad...@ex...>]

I had a problem with a type data conversion, in this case with
effectiveBooleanValue being called on AbstractDateTimeValue.

I could not find the cause of the error, and so I 'hacked' the code to
push the calling expression into the type comparisson, so that I could
then extract the line and column numbers of the calling XQuery to
annotate the XPathException that was thrown.

This is just a simple example, see the attached diff, but I am
wondering if there is value in, expanding on this concept and pushing
xquery line context information into the datatype system for better
errors.

A cleaner approach might be to change the exceptions thrown by the
types, then catch them in the expression, add the expression
information and then throw them as XPathExceptions?

The following xquery -

if(current-dateTime())then
()
else()

Will cause the error I was seeing, with my patch applied you will also
get the line number of where the error in the XQuery occurred.

Thoughts please :-)


-- 
Adam Retter

eXist Developer
{ United Kingdom }
ad...@ex...
irc://irc.freenode.net/existdb