[xsl] Keys, Lookup tables, Push--Pull (Was: Re: Putting parameter into XPATH expression)

[Dimitre Novatchev <dnovatchev@xxxxxxxxx>]

Wendell Piez wrote:

[snip]

> We've seen some interesting threads lately, for example examining the uses 
> of keys with lookup tables (Dimitre), that suggest some directions to 
> explore in this area. A lookup table (whether keyed, or accessed by brute 
> force) -- or, for that matter, keys in general -- is one way to "broker" 
> between a push stylesheet (push tending to be more robust and maintainable 
> than pull) and certain occasional needs to pull.
> 
> Am I making any sense? I'd like to hear from others.

Hi Wendell,

The use of pull style in my code is not a matter of taste -- it was forced, because
it is not permitted to define a stylesheet like this:


  <xsl:template match="key('kLookup', name($input))[$lookupSection = name(..)]">


If this was permitted, I would have this template defined and it would be
instantiated through:

  <xsl:apply-templates/>

Also, to ensure that the key() function would be applied on the right document it is
necessary to switch between documents using a xsl:for-each like this:

  <xsl:for-each select="document('lookup.xml')">


The result is that the code ***must*** use pull style.


Maybe, it could be possible, by changing the syntactic/semantic rules for defining a
xsl:template in future versions of XSLT, to allow pure push style to be used in
cases like this?
        
Personally, I'm not a fanatical supporter of "pure push style" and can happily live
with the current situation -- this would really matter if not only aesthetic
considerations were involved.

Cheers,
Dimitre Novatchev.
     

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