RE: [xsl] controller stylsheet. performance, best practices question

["Michael Kay" <mhk@xxxxxxxxx>]

An alternative you might consider is the Novatchev "dynamic templates"
method.

Change

<xsl:template name="xyz">

to

<xsl:template match="xyzPage" mode="switch">
  <xsl:param name="$current-node"/>

Create an element <xyz/> (e.g. in a document switch.xml)

Change

<xsl:choose>
  <xsl:when test="$p='xyz'">
    <xsl:call-template name="xyzPage"/>
  etc. etc.

to

<xsl:apply-templates
select="document('switch.xml')/switch/*[name()=$p]">
  <xsl:with-param name="current-node" select="."/>
</xsl:apply-templates>

For greater efficiency, use keys.

Michael Kay
Software AG
home: Michael.H.Kay@xxxxxxxxxxxx
work: Michael.Kay@xxxxxxxxxxxxxx  

> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx 
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Terence Kearns
> Sent: 23 April 2003 07:46
> To: XSL-List@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] controller stylsheet. performance, best 
> practices question
> 
> 
> In an application I'm building, I've found myself applying an MVC 
> pattern to how I call templates. I have once stylesheet used 
> by all my 
> web-based server scripts (PHP scripts). This website then calls 
> different templates based on the context of the script.
> Here is the script, questions to follow:
> 
> <?xml version="1.0" encoding="UTF-8"?>
> <xsl:stylesheet
>      version="1.0"
>      xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
> 
>      <!-- import templates implementing dynamic content -->
>      <xsl:import href="xsl-inc_finder.xsl" />
>      <xsl:import href="xsl-inc_subjects.xsl" />
>      <xsl:import href="xsl-inc_requirements.xsl" />
>      <xsl:import href="xsl-inc_listing.xsl" />
>      <xsl:import href="xsl-inc_login.xsl" />
> 
>      <!-- set context used by the controller -->
>      <xsl:param name="op" select="'<?php echo @$_GET["op"]; ?>'" />
> 
>      <!-- BEGIN MAIN PAGE TEMPLATE-->
>      <xsl:template match="/">
>              <!-- blah blah blah. masses of literal content 
> goes here -->
> <!-- CALLS TO THE MAIN CONTENT BEGIN HERE -->
>                  <xsl:choose>
>                      <xsl:when test="$op = 'finder'">
>                          <xsl:call-template name="finderPage" />
>                      </xsl:when>
>                      <xsl:when test="$op = 'subjects'">
>                          <xsl:call-template name="subjectsPage" />
>                      </xsl:when>
>                      <xsl:when test="$op = 'login'">
>                          <xsl:call-template name="loginPage" />
>                      </xsl:when>
>                  </xsl:choose>
> <!-- CALLS TO THE MAIN CONTENT END HERE -->
>              <!-- blah blah blah. masses of literal content 
> goes here -->
>      </xsl:template>
>      <!-- END MAIN PAGE TEMPLATE-->
> 
> </xsl:stylesheet>
> 
> 
> 
> Functionally, this appoach seems to work well for me. My 
> questions is: Is taking this sort of approach prone to big 
> performance problems? I can see that in many cases, most of 
> the templates imported at the top 
> of the style sheet will not even be used. They can't be 
> included on the 
> fly because they need to be top-level (can't be nested inside IF or 
> CHOOSE).*
> 
> Any other observations about the merits of this approach appreciated.
> 
> cheers.
> 
> * I could probably use PHP code to include it on the fly, but 
> I want to 
> avoid doing so because I've made a rule for myself not to use 
> server-side code embedded in the stylesheet. I've done so in 
> the param 
> of this example for purposes of clarity, normally I would 
> send them to 
> the processor directly from the PHP function call.
> 
> 
> -- 
> Terence Kearns: Web Developer
> University of Canberra: +61 2 6201 5516
> 
> 
> 
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> 


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