Re: testing for string and number in XSLT 2.0 was Re:

Michael Kay wrote:

>>EX. XML
>><?xml version="1.0" encoding="UTF-8"?>
>><example>
>>    <test>132131</test>
>></example>
>>    
>>
>
>I'll assume there is no schema, that is, this is an untyped/unvalidated
>document.
>  
>
yes, like much of the xml in existence.

>>    <xsl:variable name="x" select="example/test" as="xs:integer"/>
>>    <xsl:variable name="y" select="example/test"/>
>>
>>        y variable value(so we know we are selecting it): 132131
>>        Test y as string:false
>>        Test y as integer:false
>>        x variable value:132131
>>        test x as integer: true
>>
>>not sure if this is what I would expect normally, the issue is related
>>to an element if if has no explicitly declared data-type..
>>    
>>
>
>I don't know what your expectations are but these results are correct
>according to the spec. If you don't validate the input document against a
>  
>

>schema, then the "typed value" of its nodes is untypedAtomic. If you test
>($y instance of xdt:untypedAtomic) you will get the answer true.
>untypedAtomic behaves essentially like XSLT 1.0 - if you use the value where
>a string is expected, it's treated as a string, if you use it where an
>integer is expected, it's converted to an integer.
>  
>
>>it doesnt make much sense to me to *have* to declare something as an
>>integer datatype to test if its a value is a number...whats the point?
>>
>>    
>>
>You need to distinguish "instance of" and "castable as". The "instance of"
>  
>
I think I have enough understanding of the two.

>operator is useful if you write a function that can accept arguments of
>several different types and you want to test which type you have been given
>(just like "instanceof" in Java). The "castable as" operator is useful when
>you are given untyped data and you want to see whether its lexical form
>makes it suitable for casting to a particular type such as xs:integer or
>xs:date - which is where this thread started.
>  
>

doing

        y variable value(so we know we are selecting it): <xsl:value-of
select="$y"/>
        Test y as string:<xsl:value-of select="$y castable as xs:string"/>
        Test y as integer:<xsl:value-of select="$y castable as xs:integer"/>

comes up with

        y variable value(so we know we are selecting it): 3123123
        Test y as string:true
        Test y as integer:true

back to my original question, how can I test if a value is a string or
integer (with the very real constraint of data not being explicitly typed).

not having a go, just think that this is a pretty valid use case.

--Jim Fuller