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Re: expression must evaluate to a nodeset / shortcuts !

2002-11-05 04:23:00

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.

after

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


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

<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)

David

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