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

2010-02-04 03:45:29
 http://www.w3.org/TR/2007/REC-xpath20-20070123/#id-castable
 "[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:

 http://www.w3.org/TR/2007/REC-xpath20-20070123/#doc-xpath-StringLiteral

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
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/

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