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https://issues.apache.org/jira/browse/XALANJ-2510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12787413#action_12787413
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Martin von Gagern commented on XALANJ-2510:
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Changes to behaviour depending on element context feel like a really bad idea
to me. This is because what the user intends and how the element interprets the
situation might be quite different things. For example if I as an innocent user
of that library were to use some conditional like Henry suggested, and ended up
accidentially setting some global entity manager, I might become quite unhappy.
So from the user perspective, I would wish for the behaviour of elements to not
depend on context. Instead I'd prefer some attribute to change behaviour where
appropriate, e.g. defaultManager="yes|no" or output="object|stderr" or whatever.
As for the implementation, how about using placeholder elements? The custom
elements could return <placeholder xmlns="some-internal-namespace" index="42"/>
and keep track of the association from the index 42 to the actual object in
some kind of auxiliary data structure available for the whole process, e.g.
through an Object-valued xslt variable set by the caller. The fact that you
already have a global default manager suggests you know a suitable way to get
such per-transformation variables. Functions dealing with the objects
represented by such placeholders could then inspect whether the node (list)
they are given is a placeholder, maybe with some whitespace around it, and if
so, retrieve the associated object and use that.
The benefit would be that all of this could be implemented in the extension
library, without any modifications to xalan itself. It would therefore be much
easier to deploy, and much easier to port to other processors. Furthermore
there'd be much less corner cases to deal with, e.g. what would happen when
arbitrary objects end up getting serialized to xml. And with the use of
placeholder elements instead of opaque object variables, users would have all
the power of xslt at their disposal; not only conditionals and template
invocations, but arbitrary third party extensions as well.
> Ability to set non tree fragment variable using an extension element (PATCH
> SUPPLIED)
> -------------------------------------------------------------------------------------
>
> Key: XALANJ-2510
> URL: https://issues.apache.org/jira/browse/XALANJ-2510
> Project: XalanJ2
> Issue Type: Improvement
> Security Level: No security risk; visible to anyone(Ordinary problems in
> Xalan projects. Anybody can view the issue.)
> Components: Xalan-extensions
> Affects Versions: The Latest Development Code
> Reporter: Adam Jenkins
> Fix For: The Latest Development Code
>
> Attachments: XALANJ-2510.patch
>
>
> When using extension elements, there is no way to set a non XRTreeFrag
> related variable.
> For example, say you have:
> <xsl:variable name="myvar">
> <my:extension someAttribute="somevalue"/>
> </xsl:variable>
> If my:extension wants to set a tree fragment, string or nodeset into myvar,
> that's not a problem, however if it wants to set a java object, currently
> there is no mechanism for that (any java object passed either returned from
> the method or passed to XSLProcessorContext.outputToResultTree is
> toString()'ed before being passed back to the ElemVariable.getValue() method).
> The proposed change (patch supplied) is to supply an optional variable on
> ElemVariable.java whereby child extension elements can call up to their
> parent and set an XPath to be evaluated after the extension element has
> finished processing.
> This requires only very minor modification to the ElemVariable.getValue
> method to check this variable.
> This also ensures that this is optional functionality and will not affect
> that basic Xalan processing.
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