Re: [xsl] Cannot use a parameter value in the group-starting-with attribute?

[David Carlisle <davidc@xxxxxxxxx>]

On 14/05/2010 20:49, Peter Desjardins wrote:
> Hi. I'm writing a 2.0 stylesheet and my processor is Saxon HE 9.2.1.1.
> Also, I'm just starting out with XSLT.
>
> I am trying to create a template with parameters that will use the
> for-each-group element. I find that I cannot use a parameter value in
> the group-starting-with attribute.

There are two problems there, one is that patterns use a restricted 
syntax compared to xpath, but more importantly parameters and variables 
in xpath hold _values_ (as they would in c or fortran) not fragments of 
syntax 9as they would in a shell scripting language)

so when you go   <xsl:with-param name="starting-element" select = "h1" />

the parameter does not hold the fragment of a pattern "h1" it holds the 
result of ebaluating teh expression h1 at that point, which is a 
possibly empty  sequence of h1 nodes.

the this works

  <xsl:for-each select = "$starting-element">

but it is not (at that point) selecting h1 elements it is simply 
iterating over the list of elements that has already been selected and 
stored in the $starting-element variable.

but this could not work even if it were not a syntax error

<xsl:for-each-group select = "*" group-starting-with = "$starting-element">

the grouping attributes need to take patterns or expressions used to 
filter the nodes selected, not take a sequence of nodes.

so do not pass in a sequence of nodes, pass in a string:

<xsl:with-param name="starting-element" select = "'h1'" />

(note the extra quotes(

then you can use that string in a pattern


<xsl:for-each-group select = "*"
group-starting-with = "*[name()=$starting-element]">


David