Re: [xsl] New user issue: use of Muenchian method

Subject: Re: [xsl] New user issue: use of Muenchian method
From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>
Date: Fri, 21 Sep 2007 14:21:47 -0400
Hey Mike,

To cross with another thread --

At 10:05 AM 9/21/2007, you wrote:
<xsl:stylesheet version="2.0" ...

If you are using XSLT 2.0 I strongly recommend you investigate its native grouping facilities before investing too much energy into the Muenchian method, which is essentially a hand-made implementation of an algorithm to handle processing semantics that could have been much more deeply embedded in the language -- and which now, in XSLT 2.0, have been.

This having been said, what you are now doing isn't (yet) a full-blown example of the Muenchian method. So far as I can see, it's simply the (appropriate) use of a key to perform node traversal according to an association between nodes.

It seems to me that Ken has done his usual fine work analyzing your stylesheet, but there's one other possible problem I see:

  <xsl:value-of select="text()"/>
  <xsl:for-each select="key('entity-id','@id')">

... you'd probably want select="key('entity-id',@id)". At present, you are using the string value "@id" as your key value -- probably not what you want.

It also appears that the basic issues you're having relate to the XSLT processing model -- how nodes are matched by templates and processed, and most especially how they're matched by templates and processed by default, even if you have no explicit logic for doing so. That's why Ken advises you also to read up on the built-in templates.

One thing I have students work out when they're at this stage is to run a stylesheet that *has no templates* and see if they can explain why they get the output they do.

The next thing I often have them do is try a stylesheet that has only a single template, which matches a single type of element deep in their tree. For example, you could have

<xsl:template match="Referenced_Entities">

... and then explain the results of that. (Some people find the first task much easier after they've tried the second.)

It gets even more interesting if you had a second template to the mix:

<xsl:template match="Subject_AreaProps">

The key to all of it is in seeing what the templates are doing *together* -- which includes those helpful (but invisible) built-in templates.

Any XSLTer who can't tell you what you'll get and why is either still a beginner, or a poser. :-)


Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.      
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