Re: [xsl] expression must evaluate to a nodeset / shortcuts !

Subject: Re: [xsl] expression must evaluate to a nodeset / shortcuts !
From: David Carlisle <davidc@xxxxxxxxx>
Date: Tue, 5 Nov 2002 11:23:00 GMT
> Is there a workaround for this?

not really. Some systems have an evaluate fextension function to
evaluate a string as an Xpath. But you ask

> Why i can use

but the question is  "why would you expect that" (and others too, you are
not teh first to ask, this is a FAQ)

Most languages have the same restriction.


<xsl:variable name="path" select=" '/root/body/filter/df/@name'  "/>

$path is a _string_ containing a bit of XPath syntax.

<xsl:value-of select="$path='gspkennung'/@title"/>

is legal but means the same as

<xsl:value-of select="'/root/body/filter/df/@name'='gspkennung'/@title"/>
and tests those two strings.

this is just the same as C or most otehr languages, in C if you have the
string "x + y" you can't easily get from there to the sum of teh
variables x and y unless you write a parser for teh string that maps
that string syntax to the expression language. That's what the
xx:evaluate() function does for you if your system has that extension
(saxon and xalan at least have such an extension)


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