Re: [xsl] [XSLT 2.0] Checking that an element's value has the desired datatype?

[David Carlisle <davidc@xxxxxxxxx>]

> As best I can tell, the functionality of Schematron + xPath 2.0 is a
> superset of XML Schemas (and RelaxNG). 

There is one major piece of XSD functionality that is not available in
schematron or Relax NG. XSD schema does not just validate the input, it
_annotates_ the input returning a PSVI. The fact that it does this
rather than returning the original XML document is highly controversial
still and one of the main design considerations for relax NG was that it
did not do that. However it's undeniable that XSD has this
functionality and that a large part of the design of XPath2 is designed
to use that functionality.

You can check in the stylesheet (or equivalently with schematron) that
flt:Aircraft/flt:Altitude is an integer (or decimal or whatever type you
want) but it is then your responsibility to choose an appropriate code
path. If instead you schema-validate and then use a schema-aware
stylesheet then not only does the schema check that the input is an
integer, the input tree is modified so that this type information is
permanently attatched to the data, which means that you don't need to
use number() in places like:
number(flt:Aircraft/flt:Altitude) gt number($j/flt:Height + $j/flt:Elevation + 500) 
The system would know that flt:Aircraft/flt:Altitude was a number
without being told every time, and if you use the data in a place where
an integer is not allowed, it will generate an error rather than
assuming you want to use the element content as a string.


David