Re: [xsl] are all strings in a sequence valid potential QNames

Subject: Re: [xsl] are all strings in a sequence valid potential QNames
From: Andrew Welch <andrew.j.welch@xxxxxxxxx>
Date: Thu, 4 Feb 2010 09:45:05 +0000
>> >
>> >  "[if] the input argument of the expression is of type xs:string but it
>> > is
>> >   not a literal string, the result of the castable expression is false."
>> To help me understand that :-)
> Not a problem, Andrew ... I get asked about this terminology in the
> classroom.
>> can you provide an example of a user
>> constructed string that is not a string literal?
>> For example, tokenizing a string into a sequence of strings... they
>> are all string literals aren't they?
> Nope ... a string literal is "literally a string in the stylesheet" written
> with string delimiters.  The term "literal" here is in reference to the
> XPath written syntax.
> A sequence of strings is just that: a sequence of string values in memory.
> A literal string in the stylesheet is just that:  a string value literally
> delimited in the stylesheet.  See production 74 of the XPath syntax:
> The difference is a syntax issue:  a string literal is a type of primary
> expression (production 41) written in the stylesheet syntax and it is the
> way to represent a string value in the XPath syntax different from the
> representations of other literal values.
> I hope that clarifies the distinction.

It does, thanks Ken.

Doesn't that restriction then make "castable as xs:QName" pretty
useless?   I can't see when you would need it...

Andrew Welch

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