Re: New axes?

I agree with Michael Kay that it would probably be better to define
this as a function. Otherwise, it might not be very obvious what
sibling::*[1] is supposed to return. Next, people might expect an
equivalent
vertical axis that combines descendants and ancestors.
____________________________________

On Wed, Dec 2, 2020 at 2:05 PM Edward Porter <Edward.Porter@sas.com> wrote:
>
> If adding syntactic sugar next:: and previous::, could we also consider adding sibling:: to look in both directions? All three would make for more readable xpath, in my opinion.
>
> -----Original Message-----
> From: Christian Grün <cg@basex.org>
> Sent: Wednesday, December 2, 2020 5:08 AM
> To: Michael Kay <mike@saxonica.com>
> Cc: Norm Tovey-Walsh <norm@saxonica.com>; public-xslt-40@w3.org
> Subject: Re: New axes?
>
> EXTERNAL
>
> An alternative would be to introduce new functions:
>
>   fn:next-sibling($node as node()?) as node()?
>   fn:previous-sibling($node as node()?) as node()?
>
> Similar to fn:has-children, we cannot perform straightforward node tests. The requirement for such tests may depend on the use cases we are trying to solve.
> ____________________________________
>
> On Wed, Dec 2, 2020 at 10:51 AM Michael Kay <mike@saxonica.com> wrote:
> >
> > It's a fairly cosmetic change to get rid of a minor ugliness. People often forget the [1] qualifier when they only want the immediately following sibling, and the difference between preceding-sibling::*[predicate][1] and preceding-sibling::*[1][predicate] isn't intuitive.
> >
> > The problem of course is that you can never get rid of a danger point on a well-trodden road by providing a new shiny road; the very people who fall into the trap will be unaware of the new features.
> >
> > Michael Kay
> > Saxonica
> >
> > On 2 Dec 2020, at 09:38, Norm Tovey-Walsh <norm@saxonica.com> wrote:
> >
> > Michael Kay <mike@saxonica.com> writes:
> >
> > How would anyone feel about adding new axes next::* and previous::* to
> > get the first following/preceding sibling?
> >
> > Or next-sibling / previous-sibling if people prefer long names.
> >
> > It would have to be that next::* means following-sibling::*[1]
> >
> >
> > Can next::* ever be different from (following-sibling::*)[1]?
> >
> > Another two candidates are following-sibling-or-self::* and
> > preceding-sibling-or-self::*, with hopefully obvious semantics.
> >
> >
> > What are the use cases for these?
> >
> > To me, it feels like adding a new axis is a fairly heavyweight change.
> > There are already quite a few axes and I think users sometimes
> > struggle to understand them. I’m not saying we must not add new axes,
> > but I’d like to be convinced that their utility justifies them.
> >
> >                                        Be seeing you,
> >                                          norm
> >
> > --
> > Norm Tovey-Walsh
> > Saxonica
> >
> >
>

Received on Wednesday, 2 December 2020 13:17:32 UTC