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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