CODEWITHSUNDEEP
xsltimportxslt-1.0global
Peter Krauss
Peter Krauss

Reputation: 13940

xsl:import conventions about general stylesheet's properties

The XSLT1 spec, xsl:import section is not very clear/direct about things like:

I have a "hub XSLT" with all attributes and global tags... But now I am importing some XSLTs that are also standalone XSLTs, so perhaps in the future I will notice surprises... To avoid surprises, this question.

Summarizing the question:

Can all the XSLTs be "empty of gobal tags" if the "hub XSLT" has all of them? If there is conflict, what are the precedence rules?

Upvotes: 2

Views: 150

Answers (1)

Mathias Müller
Mathias Müller

Reputation: 22637

You are asking if it is sufficient to have all the declarations only in the importing module, but at the same time you are saying that all modules are also "standalone" XSLT stylesheets? Makes no sense to me. Obviously, an imported module would not be a full-flegded stylesheet anymore if it did not have declarations and, in the case of missing namespace declarations, it would not be well-formed XML anymore. And a stylesheet that is malformed XML would be utterly useless.

In general, imported declarations (declarations that physically reside in the imported stylesheet module) have a lower precedence. But some qualifications are needed.

xsl:output/@method

xsl:output is a declaration, if there is conflict between stylesheets, the importing module takes precedence over the imported one. Consequently, the output method declared in the importing stylesheet will be used. But a caveat here: not all attributes of xsl:output are treated in the same way.

Namespaces

Namespaces (and thus prefixes) that are defined in the importing stylesheet are not available in the imported stylesheet. This means that if you define 

xmlns:ns="www.namespace.com"

in the importing stylesheet, the prefix ns will not be connected to the namespace URI "www.namespace.com" in the imported module. In such a case, you need to redeclare the namespace.

And if you ponder this fact for a while, it becomes obvious why this is so: A stylesheet (module) does not need to be imported. It should always be possible to use it on its own or import it. The only way to make sure a stylesheet retains its independence is to declare all namespaces in it.

exclude-result-prefixes

For attributes like exclude-result-prefixes I quote Michael Kay1, saying that

[t]he values of the version,extension-element-prefixes,exclude-result-prefixes and xpath-default-namespace attributes that apply to an element in the imported stylesheet, as well as xml:lang and xml:space, are those that were defined in the <xsl:stylesheet> element of their own module, not those on the <xsl:stylesheet> element of the importing module.

The easiest way to find the rules would of course be to simply test. In most cases, the test would be a pretty trivial one. For example, define two output methods in the stylesheet modules:

<xsl:output method="text"/>      <xsl:output method="xml"/>

and see if the output is text or XML.

And that's exactly how you should go about finding the rules for "...etc..." from your question.

1 Michael Kay, XSLT 2.0 and XPath 2.0 Programmer's Reference, p. 358

Upvotes: 2

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