Re: XSLT 4 xsl:with

On Thu, May 21, 2020 at 05:58:14AM -0000, Michael Kay mike@xxxxxxxxxxxx scripsit:
> This reminds me that I've been trying to find a good syntax for doing
> 
> <xsl:for-each-member-in-array select="[(1 to 3), (5 to 9), (10 to 20)]">
>    <x>{count(current-member())}</x>
> </xsl:for-each-member-in-array>
> 
> where the result is 
> <x>3<x><x>5</x><x>11</x>
> 
> I have a general distaste for adding more bits and pieces to the dynamic context (current-this() and current-that()). They all clutter the space, they have messy static and dynamic scoping rules, and you often end up binding them to variables anyway. I would prefer to bind explicit variables: in some drafts of XSLT 3.0 we used binding variables on xsl:for-each-group, and that's what saxon:for-each-member currently does:
> 
> https://saxonica.com/documentation/index.html#!extensions/instructions/for-each-member
> 
> <saxon:for-each-member select="[(1 to 3), (5 to 9), (10 to 20)]" bind-to="m">
>    <x>{count($m)}</x>
> </saxon:for-each-member>
> 
> What do other people feel? Should we have @bind-to on other things like xsl:for-each and xsl:for-each-group?

@bind-to as a replacement for current-group() would be fine, but!

I would hate to lose current-grouping-key(); that often winds up being
used as a map key or going into an attribute.  I would expect we could
have a bind-key-to attribute as a replacement for current-grouping-key()

I'd want for-each to have @bind-to as a way to save the context item.  I
presently find myself sticking dot in a variable fairly often, just so I
don't lose it in the contents of the for-each.

I'd like to be able to attach a type to the @bind-to and @bind-key-to
variables, which would mean they'd have to be elements

<xsl:for-each select="1 to 100">
  <xsl:bind-to name="context" as="xs:integer"/>
  ... do stuff....
</xsl:for-each>

If we're considering opening up for-each and for-each-group, some analog to the XQuery "at",

for $x at $count in $stuff

would be welcome.  Don't want it often but it's a pain not to have it
when it is wanted.  I don't have a good feel for for-each-member but
have a suspicion an "at" would be useful there as well.  bind-index,
whether as an attribute or an element?

> The other approach to the above construct is to do it all in XPath. You can also do this in Saxon 10:
> 
> <xsl:sequence select="[(1 to 3), (5 to 9), (10 to 20)] => array:for-each(_{saxon:new-element("x", string(count($1))})"/>

This is powerful and useful and it gets so hard to read.  I'd prefer to
have a "write it out longhand" option as well as the XPath.

-- 
Graydon Saunders  | graydonish@xxxxxxxxx
^fs oferiode, pisses swa mfg.
-- Deor  ("That passed, so may this.")