Re: [xsl] except

["Imsieke, Gerrit, le-tex" <gerrit.imsieke@xxxxxxxxx>]

On 02.02.2014 22:50, Graydon wrote:
> descendant::* except heading
>
> is really "all the descendant elements without any child heading
> elements of the context node", and that's usually a source of
> intractable bugs.  I think it should be
>
> descendant::* except self::heading
>
> if I want all the descendant elements without any of the descendant
> elements who happen to be heading elements.

If you want that and if you insist on using except instead of the 
classic filtering by predicate,

  descendant::*[not(self::heading)] ,

you can easily write:

  .//(* except heading) ,

which (partially) expands to

  ./descendant-or-self::node()/(* except heading) .

I think you'll just have to remember that the sequences on both sides of 
except will be evaluated from the same context.

This clear but apparently sometimes counterintuitive semantics of except 
should not change if the expression has some special characteristics. 
For example, as you suggest, when the expression on the left looks down 
the descendant axis and the expression on the right, under normal (= 
mathematically sound) circumstances, would look on the child axis.

Gerrit