On Apr 10, 2005 3:59 AM, Michael Kay <mike(_at_)saxonica(_dot_)com> wrote:
I repeated your experiment with Saxon 8.4, changing only the variable
definition of $y to:
<xsl:variable name="y" select="data(example/test/text())"/>
and still got:
$y variable value: 132131
Test as string:false
Test as integer:false
It seems to me that the test as xs:string should be positive, because
the typed value of a text node must be by definition xs:string.
No, the typed value of a text node is by definition untypedAtomic - see
http://www.w3.org/TR/xpath20/#id-typed-value
untypedAtomic is a chameleon type that is automatically cast to the type
required by the context where it is used.
Yes, I saw this in the spec, too.
I have two questions:
1. What was the reason for the decision that the typed value of a
text node must be of type xdt:untypedAtomic ? If the node is a *text*
node, then its value must be *text* -- that is *string*.
2. I didn't find in the F & O spec any explanation why a value
comparison (such as lt) of two xdt:untypedAtomic values treats them as
strings. Why not as integers? Why/how this happens? Is there something
like a "preferred/default datatype" for the value-comparison
operators? Isn't it more practical to have xs:string as the chameleon
datatype?
For example, I have this source xml document:
<t>
<num>1</num>
<num>02</num>
</t>
and this transformation:
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns:xdt="http://www.w3.org/2005/02/xpath-datatypes";
exclude-result-prefixes="xs xdt"
<xsl:template match="/">
<xsl:variable name="v1" select="data(/*/*[1])"/>
<xsl:variable name="v2" select="data(/*/*[2])"/>
$v1: '<xsl:value-of select="$v1"/>'
$v2: '<xsl:value-of select="$v2"/>'
$v1 instance of xdt:untypedAtomic: <xsl:value-of select="$v1
instance of xdt:untypedAtomic"/>
$v2 instance of xdt:untypedAtomic: <xsl:value-of select="$v2
instance of xdt:untypedAtomic"/>
$v1 lt $v2: <xsl:value-of select="$v1 lt $v2"/>
$v1 gt $v2: <xsl:value-of select="$v1 gt $v2"/>
</xsl:template>
</xsl:stylesheet>
produces this result:
$v1: '1'
$v2: '02'
$v1 instance of xdt:untypedAtomic: true
$v2 instance of xdt:untypedAtomic: true
$v1 lt $v2: false
$v1 gt $v2: true
So we see that the two values of type xdt:untypedAtomic are treated as
xs:string by the value-comparison operators.
Cheers,
Dimitre Novatchev
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