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Re: [xsl] [XSLT 3.0]


Subject: Re: [xsl] [XSLT 3.0]
From: Michael Kay <mike@xxxxxxxxxxxx>
Date: Thu, 01 Nov 2012 08:17:39 +0000

Option A is fine. (This is nothing really to do with function items, the answer would be the same if you were talking about a sequence containing elements and text nodes...)

"treat as" is never needed in systems that do dynamic type checking. It makes an assertion about the dynamic type which basically tells a static type system to defer type checking till run-time. But as far as I know all XSLT 2.0 processors do this anyway without being asked. There are a few XQuery processors that don't (e.g. the one from Microsoft), but they aren't widely used.

Michael Kay
Saxonica

On 01/11/2012 01:32, sean@xxxxxxxxxxxxxxxxx wrote:
Suppose that $state is a sequence which contains, among other things, at least one function item with signature...

function(element(square)*) as element(square)*

Which is the correct and safe way to store a reference to this function in a variable?

Is it OPTION A?

    <xsl:variable name="compute-possible-moves"
         select="$state[. instance of function(*)][1]"
         as="function(element(square)*) as element(square)*">

... OR OPTION B?

<xsl:variable name="compute-possible-moves"
select="$state[. instance of function(*)][1]
treat as function(element(square)*) as element(square)*"">


... OR OPTION C?

    <xsl:variable name="compute-possible-moves"
         select="$state[. instance of function(*)][1]
                 treat as function(element(square)*) as element(square)*"
         as="function(element(square)*) as element(square)*">

My best estimate at the moment, would be option A, but I am not really sure about it.


Faithfully, Sean B. Durkin


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