Re: [xsl] local variables as entity reference in different stylesheets

[Jeni Tennison <jeni at jenitennison dot com>]

Hi Marko,

> Well, now that I think of it: I'm as surprised as you are! msxsl-bug?
>
> This works:
>
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; version="1.0" >
> <xsl:output method="text" encoding="iso-8859-1" />
> <xsl:template match="/">
> <test> <!-- some root element -->
> <xsl:variable name="dummy" select="1"/>
> </test>
> <xsl:value-of select="$dummy"/> <!-- $dummy is known and output will be 1 -->
> </xsl:template>
> </xsl:stylesheet>

Cripes, you're right! That's definitely a bug, in both MSXML 3 and 4.
Will you report it?

> The XSLT-part is used to create sql-scripts, (selects, inserts,
> updates and deletes) which explains why I don't care about result
> trees: the output method is text. So the trick here is that the root
> element is only used to apply the xsl-namespace.

Good. I was thinking of other possibilities before I realised that the
root element would give you variable scoping problems, and if you
*were* worried about result elements then the best thing would
probably be an xsl:if:

<xsl:if test="true()"
        xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
  ...
</xsl:if>

(Note that this *doesn't* work with MSXML :)

Interestingly enough, with processors other than MSXML (e.g. Saxon,
Xalan, libxml) you don't have to worry about the namespace
declarations in the external document at all because the entities are
resolved before the namespace prefixes are checked.

> In fact I already make use of your suggestion to call named
> templates to fill them, by starting of each stylesheet with an
> <xsl:include href="templates.xsl"/>. I just thought it would be
> shorter and less prone to typing errors to use [entity references].

Yes, it probably is. I just think using entities is a bad idea in
general because you lose information about them when you process the
XML - if you were to run your stylesheets through some other
transformation, for example.

Thinking along those lines, you could try an approach where you
included something like:

  <my:variables />

in your stylesheets and ran them through another XSLT process to
substitute in the variable declarations, and use the result of that
transformation as the stylesheet in your later transformations.

For a generic language along those lines, you could use XInclude to
encode the inclusion, with XPointers that point past the root element
in your included document to the variable definitions that you're
actually interested in. Of course you'd have to use an
XInclude-and-XPointer-aware pre-processor to resolve them. The
advantage of entities is that most basic XML parsers will do the job
for you.

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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