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Re: [xsl] attribute value templates in elements fetched from a map?

2020-09-03 10:43:09
 Is that a bit less like nonsense?

I personally still don't understand the problem...

A simple, complete example may be helpful.

Dimitre

On Thu, Sep 3, 2020 at 7:23 AM Graydon graydon(_at_)marost(_dot_)ca <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

On Wed, Sep 02, 2020 at 10:27:17PM -0000, Martin Honnen
martin(_dot_)honnen(_at_)gmx(_dot_)de scripsit:
I don't understand where you use xsl:evaluate and where you bind the
value to $calculated.

Let me try to give less ambiguous context!

I've got a few hundred source elements; these group into a small number of
structural categories.  (block, table, inline, link, etc.)  That happens
via map lookup:

<xsl:template match="*[$categoryMap(name()) = 'block']>
...structure markup goes here....
...something has to define the style...
</xsl:template>

That part works.

Inside the structure markup, there's an element that defines the rendering
style.  There are many more rendering styles than there are structures, but
many fewer than input element names; perhaps a hundred.  The rendering
style is usually but not always a simple mapping between the element name
and a style name, and I could -- for at least 80% of the cases -- store
that in the same map as element markup if I went from

map(xs:string,xs:string)
to
map(xs:string,map(xs:string,item())

So the grouping templates would use

<xsl:template match="*[$categoryMap(name())('groupname') = 'block']>
....
</xsl:template>

and the style would use
<xsl:sequence select="$categoryMap(name())('style')"/>

and retrieve the style markup appropriate to this input element name.

This is attractive because I could keep all the details in the map, making
long term maintenance simpler; the templates and the logic are stable and
behaviour gets driven from the map, making it easy to add new elements or
change a style.

The problem is that it isn't always a static style; sometimes other
information that depends on the input element context is required, such as
title depth. (title depth = "how many of my ancestors have titles?") This
means there's extra/different markup in the style definition and a value
that isn't statically derived from the element name. What I want to do is
to store the style markup in the map in the same way, and populate it with
the specific values somehow after I retrieve it.

So far,
- anonymous functions are an awkward and doubtful way to create nested
  elements in the result tree; might as well just call a regular XSLT
  function directly and encapsulate the source-element-to-style mapping
  in that function
- evaluate doesn't get me anything because I can xsl:evaluate XPath, but
  not markup, so this isn't a way to process the elements retrieved from
  the map to populate values
- there isn't any way (that I know of) to say "plunk this block of
  markup into the evaluation context like we called xsl:call-template
  and this markup retrieved from the map is what was in the template we
  called"
- there isn't any way (that I know of) to put an attribute value
  template in the element markup in the map and have it evaluated at
  retrieval time.

What I want to know is if I'm missing something, and there's a way to get
element markup back out of a map and put it into evaluation context without
having to use transform() and start a whole new process and pass in the
whole input document for context anyway.

(It's quite possible I am falsely enamoured of an opportunity for neatness
and should not try to keep all of this "input element maps to" information
in the same place.  It still feels like there ought to be way.)

Is that a bit less like nonsense?

--
Graydon Saunders  | graydonish(_at_)gmail(_dot_)com
Þæs oferéode, ðisses swá mæg.
-- Deor  ("That passed, so may this.")




-- 
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
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Never fight an inanimate object
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To avoid situations in which you might make mistakes may be the
biggest mistake of all
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Quality means doing it right when no one is looking.
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You've achieved success in your field when you don't know whether what
you're doing is work or play
-------------------------------------
To achieve the impossible dream, try going to sleep.
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I finally figured out the only reason to be alive is to enjoy it.
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