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RE: default parameters
- To: <xsl-list at lists dot mulberrytech dot com>
- Subject: RE: [xsl] default parameters
- From: "Michael Kay" <mhkay at iclway dot co dot uk>
- Date: Tue, 30 Jan 2001 21:47:16 -0000
- Reply-To: xsl-list at lists dot mulberrytech dot com
> Does anyone know how to set the default value of a parameter
> to an attribute
> value, like an id, from an element whose date attribute is
> the most recent
> out of all similar date attributes?
It can be done, but it isn't easy, especially if you want to avoid the
node-set() extension.
Firstly, a named template that converts your date to a sortable string,
something like
<xsl:template name="iso-date">
<xsl:param name="date"/>
<xsl:value-of select="format-number($date/year, '0000')"/>
<xsl:value-of select="format-number(
count(node-set($months)/month[.=$date/month]::preceding-siblings)+1,
'00')"/>
<xsl:value-of select="format-number($date/day-of-month, '00')"/>
</xsl:template>
<xsl:variable name="months">
<month>January</month>
etc
</xsl:variable>
Then build a list of iso dates in a global variable:
<xsl:variable name="all-dates">
<xsl:for-each select="//date">
<iso-date>
<xsl:call-template name="iso-date">
<xsl:with-param name="date" select="."/>
</xsl:call-template>
</iso-date>
</xsl:for-each>
</xsl:variable>
Then build a sorted list of dates:
<xsl:variable name="sorted-dates">
<xsl:for-each select="node-set($all-dates)/iso-date">
<xsl:sort/>
<xsl:copy-of select="."/>
</xsl:for-each>
</xsl:variable>
Then choose the first one in this list:
<xsl:param name="date" select="node-set($sorted-dates)/iso-date[1]"/>
Mike Kay
I forgot that you wanted the default to be not the date, but some other
derived value: you will have to carry that value around on the constructed
trees.
>
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