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Re: [xsl] best practices for using XSLT modes

2019-12-06 13:46:21
Sure, but this will have to be

<xsl:template match="@val[. >= 0]">{ . || ': positive'}</xsl:template>

or the slightly more explicit

<xsl:template match="@val[. >= 0]">{ string(.) || ': positive'}</xsl:template>

since by matching the attribute, we have changed the context of XPath
evaluation.

Of course it could all be rearranged as well. I might prefer templates
in a mode that return nothing label, then use a generic match on @val
that emits the value and performs the concatenation, calling the moded
template for the label.

Cheers, Wendell

On Fri, Dec 6, 2019 at 1:26 PM Eliot Kimber ekimber(_at_)contrext(_dot_)com
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Whiltespace is definitely a concern.

I especially dislike things like:

<xsl:value-of>, <xsl:value-of> (would be even worse if that was just 
xsl:template instead of xsl:value-of). It's easy for fiddly bits to be 
misread or lost in code cleanup or whatever.

So I tend to prefer either xsl:text or xsl:value-of with concat() or, XPath 
3, "||" operator.

Using a text value template as the sole value of a template I think will 
satisfy my need for explicitness:

<xsl:template match="@val[. >= 0]">{@val || ': positive'}</xsl:template>

That makes the string construction intent clear while avoiding all 
unnecessary markup and any unintended whitespace.

Cheers,

E.
--
Eliot Kimber
http://contrext.com


On 12/6/19, 11:13 AM, "Piez, Wendell A. (Fed) 
wendell(_dot_)piez(_at_)nist(_dot_)gov" 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

    Probably Eliot has in mind unintended whitespace in the results (heh).



    Whitespace. The bane of empires.



    (But oof. I can see I need to do a better job cleaning up after this 
email client.)



    Cheers, Wendell



    -----Original Message-----

    From: Eliot Kimber ekimber(_at_)contrext(_dot_)com 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com>

    Sent: Friday, December 6, 2019 10:54 AM

    To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com

    Subject: Re: [xsl] best practices for using XSLT modes



    I don't like having literal text as direct children of 
<xsl:template>--too many opportunities for unintended results, so I would use 
xsl:text where Wendel has not:



    <xsl:template match="@val[. >= 0]"><xsl:text>{ . }: 
positive</xsl:text></xsl:template>



    At which point the verbosity is essentially equal my original using 
<xsl:value-of> but maybe a little cleaner.



    Cheers,



    E.



    --

    Eliot Kimber

    
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    On 12/6/19, 9:00 AM, "Piez, Wendell A. (Fed) 
wendell(_dot_)piez(_at_)nist(_dot_)gov" 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:



        Tweaked, now in 3.0 with expand-text=’true’:



        <xsl:template match="@val[. >= 0]">{ . }: positive</xsl:template> 
<mailto:%22%3e%7b%20.%20%7d:%20positive%3c/xsl:template%3e%0d%0d%3cxsl:template%20match=%22@val%5b0>

          
<mailto:%22%3e%7b%20.%20%7d:%20positive%3c/xsl:template%3e%0d%0d%3cxsl:template%20match=%22@val%5b0>

        <xsl:template match="@val[0 
<mailto:%22%3e%7b%20.%20%7d:%20positive%3c/xsl:template%3e%0d%0d%3cxsl:template%20match=%22@val%5b0>
 > .]">{ . }: negative</xsl:template>



        (Leaving aside discussion of the comparisons.)



        In general I agree with everything that’s been said in this thread. 
Whether I would use templates this way, and whether in a mode, would probably 
depend on the case and possibly on the phase of the moon.



        Cheers, Wendell



        From: Mukul Gandhi gandhi(_dot_)mukul(_at_)gmail(_dot_)com 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com>





        Sent: Friday, December 6, 2019 12:43 AM

        To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com

        Subject: Re: [xsl] best practices for using XSLT modes



        Hi Eliot,







        On Thu, Dec 5, 2019 at 8:21 PM Eliot Kimber



        ekimber(_at_)contrext(_dot_)com 
<mailto:ekimber(_at_)contrext(_dot_)com> 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:





        but I would replace the choice that acts on different @val values 
with templates applied to the @val attribute, i.e.:





                <xsl:template match="a">



                  <val><xsl:apply-templates select="@val"/></val>



               </xsl:template>





             <xsl:template match="@val[. ge 0]">



                <xsl:value-of select="@val || ': positive'"/>



            </xsl:template>





             <xsl:template match="@val[. lt  0]">



                <xsl:value-of select="@val || ': negative"/>



            </xsl:template>









        Thanks for suggesting this. It looks intuitive.









        Note that I handle the bug in the original in that it would produce 
no result when @val is "0" (zero).









        I actually, deliberately didn't include processing for the case @val 
being zero (my XML & XSLT codes were merely examples for discussion, and were 
not a real use case). But thanks, for pointing this fact.









        The use of templates rather than xsl:choose makes the code cleaner, I 
think, puts the focus at the template level on the @val attribute, which is 
the focus of the business logic









        I agree.

















        --

        Regards,



        Mukul Gandhi









        XSL-List



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