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Re: [xsl] returning nodes which have a specific child

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> I'm w/Michael on this one, at least from the perspective of clarity and ease
> of learning. The number one confusion for me when learning XSLT a couple of
> years ago was the mysterious disappearance of all my tags, and the necessity
> of learning, as almost the first step required to get anything useful done,
> an arcane identity transformation:

As Wendell said, it depends a lot on the kind of stylesheets you write.

The original motivating use case for the design of XSLT wastransforming to a
presentational format (html or xsl-fo) and considering the case of html
for example. The default behaviour is guaranteed to generate valid html
document.


Then as you decide you need more html markup in the result, you add more
templates, and it all works very naturally.



For the kind of transformation where you are "not doing much" and so
want to start off with the identity template, the default is not so
useful, but the identity template was given as an example in xslt from
the earliest drafts. It might not be the first thing that comes in to a
beginners head, but then

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

probably isn't the most memorable thing either. Some thigs you can just
learn by rote until you get the experience to understand what the
various constructs mean.

In my own stylesheets, they are probably "identity" based in only a very
small percentage of my code. If you are stating with some in XML in an
in house markup, and generating html or xhtml, or C code or C# code, or
matlab, or maple or ... Then the stylesheets are all very different but
in all cases they have the property that you don't want _any_ of the
original markup to survive into the result.

Actually I don't usually leave the default template in action, even if I
am not overriding with an identity template. In the other cases I
usually start off with

<xsl:template match="*">
  <xsl:message select="'unexpected element: ',name()"/>
  <xsl:apply-templates/>
</xsl:template>

Then the specification for any new stylesheet project is essentially
"add new templates until the stylesheet stops complaining about elements
in the input..."


David

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