Re: [xsl] Avoiding boneheaded mistakes in XSLT?

[Michael Kay <mike@xxxxxxxxxxxx>]

> Still ignoring schema.
> My supposition is that *for the xml instance being processed*
> either the expression will or will not return a non-empty
> sequence. Hence there is a possible error.
> In this case either the first book child has an author child or not.
> Surely that information is available Mike?

The problem is that if someone writes

if (@version = "2.0") ...

and there is no @version attribute, it's very likely that the semantics 
of the vocabulary are that an absent version attribute is to be treated 
as if @version="1.0". So a warning that there is no version attribute 
would be inappropriate here. The situation where the schema doesn't 
allow a version attribute is different.

Michael Kay
Saxonica