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Re: [xsl] Position() in apply-templates

Subject: Re: [xsl] Position() in apply-templates
From: Geert Bormans <geert@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 02 Apr 2014 01:19:57 +0200

Hi David,

There is no conflict between what the references tell you

To quote the example from Jeni Tennison's post
<xsl:template match="/">
  <xsl:apply-templates select="r/a">
    <xsl:sort data-type="number" select="@at"/>
    <xsl:with-param name="p" select="position()"/>

What you read in Michael Kay's book is that the nodes in the select of the apply-templates
"r/a" are selected, ordered according to the sort statement(s) and then numbered.

The position() inside the template that will eventually pick up the nodes will have that number as its value

<xsl:template match="r/a">
<xsl:value-of select="position()"/> <= here is where the numbering of the nodes plays

What Jeni Tennison says is that the position() inside the body of the apply-templates
eg here:
<xsl:with-param name="p" select="position()"/>
will get its value from the context of the template, not from the node numbering in the select.

apply-templates will not change the context,
for-each on the other hand will create a new context

I hope that helps


At 23:18 1/04/2014, you wrote:
Can someone clarify the meaning of "position()" in apply-templates.

According to Michael's Kay's 4th edition,

"When <xsl:apply-templates> or <xsl:for-each> is called to process a
sequence of nodes, the nodes ar enumbers 1 to N in their sorted order,
and while each node is being processed. the context position is the
number assigned to that node."

But I found a 2001 post indicating that, within an
<xsl:apply-templates> instruction *itself* the context position is
just the context position of the current node (_not_ the nodes being
selected by the select attribute of <xsl:apply-templates>). That post
is here=http://www.stylusstudio.com/xsllist/200105/post90830.html

My question is "When the "number assigned to that node" (as referenced
in Kay) is considered the context position? :

A. In the predicate of the select attribute of the
<xsl:apply-templates> instruction?
B. In the select attribute of any <xsl:with-param> instructions inside
the <xsl:apply-templates> instruction?
C. In the body of the <xsl:template> called by the
<xsl:apply-templates> instruction?



"A false conclusion, once arrived at and widely accepted is not
dislodged easily, and the less it is understood, the more tenaciously
it is held." - Cantor's Law of Preservation of Ignorance.

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