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docbook / xslTNG

DocBook xslTNG Stylesheets
https://xsltng.docbook.org
MIT License
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Question about the $v:templates variable #412

Closed frank-steimke closed 8 months ago

frank-steimke commented 9 months ago

This is not an issue, but a Question.

The $v:templates is defined as document-node().

The Description says "Any templates provided in $v:templates will be used preferentially to whatever builtin templates exist.". That means i can have a sequence of templates as content. I have created two custom templates and use them successfully. The structure is like this:

<xsl:variable name="v:templates" as="document-node()">
  <xsl:document>
    <db:preface context="parent::db:book"> ... </db:chapter>
    <db:chapter context="parent::db:book"> ... </db:chapter>
  </xsl:document>
</xsl:variable>

But i wonder: is this really a valid document-node()? It does not have a single root Element, but consists of two document fragments. It does work, but i dont understand why ... i would expect the XSLT processor to complain.

The modules/templates.xml file from the xslTNG Distribution uses tmp:templates as root Element for templates. Is this also possible for custom templates in a separate file?

After all, wouldn't it be better to define $v:templates as element()* or $v:templates as element(tmp:templates)?

Kind regards, Frank

ndw commented 8 months ago

The XPath data model doesn't require a document node to have a single element child. You can have none, a text document, or one, or several. You an serialize it too. It's even possible to get an XML parser to re-injest it if you arrange for it to be an external parsed entity in another document.

I often think it's better and easier to define a top-level element, but in this case, it didn't seem necessary and it just introduces new error conditions. For example, what if the top-level element isn't named tmp:templates?

The v:templates mechanism seems sufficiently narrow and specialized that it was okay to do it this way.

frank-steimke commented 8 months ago

Thanks for the explanation. This is one for "Today i have learned...".

In section 6.1.1. in the XQuery and XPath Data Model 3.1 i see the difference between the Infoset document information item and the XPath Document Node.

Greeting, Frank

fsteimke commented 4 months ago

I think it would be nice to explain this fact. Maybe more users expect a single root element for a valid document node. I have made PR #481 .