Re: [xsl] Re: Identity transformation for XSLT 2.0

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2007-12-23 23:43 +0530, Mukul Gandhi wrote:
> On Dec 23, 2007 11:01 PM, Michael Kay <mike@xxxxxxxxxxxx> wrote:
> > The fact that something can be coded in XSLT is not itself an argument not
> > to include it in the standard function library. That argument can 
> be used to
> > show that you don't need a "+" operator, because people can always write
> > "--".
>
> I recently needed to do set difference operation in a 2.0 stylesheet,
> using Saxon 9 (basic version). I was a bit surprised to find that
> Saxon reported, "Unknown system function except()".

"except" is an operator, not a function.

> The F&O spec defines this function
> (http://www.w3.org/TR/xquery-operators/#func-except). Could you please
> tell, why this built in function not implemented in Saxon 9.
>
> As a workaround, I had to resort to $seq1[not(. = $seq2)] ...

The above is comparing _values_ of each node, not the identity of each node.

Using "$seq1 except $seq2" engages the function defined in the specification.

Note how http://www.w3.org/TR/xquery-operators/#func-except is described as:

  op:except($parameter1 as node()*, $parameter2 as node()*) as node()*

I hope this helps.

. . . . . . . . Ken


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