Re: [FR] RefTex support for zref-xr

[Gustavo Barros]

Hi Arash,

On Fri, 03 Dec 2021 at 10:40, Arash Esbati <arash@gnu.org> wrote:

> > You're right, of course. The reason I asked for one thing, and not 
> > the
> > other, is that an interested user can handle \zlabel/\zref from a
> > personal style file, but tampering with `reftex-parse-from-file'
> > becomes impractical for this purpose.
>
> Agreed.  I will prepare a small patch.

Thank you.

> Agreed.  I think adding support for zref to RefTeX is a source of
> trouble.

That's a pity, but I had to do it.  And I understand, of course.  (I may 
pester you folks about this sometime in the future, though, given a 
project I'm working on, but it is too early for that.)

> You can have a function or a variable catering completion for package
> options, depends on the use case.

That must be it.  Either way, you know much better than me here.

> I guess this was the idea.  I had a look at the list in the manual
> (section 2.7 Declared properties) and saw the Property lists and the
> properties.

> I thought \zref has an optional argument which can contain a property
> from a certain property list, e.g.
>
>     \zref[page]{labelname}
>
> I think my first idea for the alist was that each zref-module adds its
> properties to `LaTeX-zref-properties-alist' which is then used for
> completion when \zref is called.  But again, I really didn't grok the
> manual in this regard.  Are the name of property lists used somewhere?
> Or only the name of the properties in the optional argument of \zref?

Yes, there are property lists and properties, and both (technically) may 
be used independently.

The property lists may be used when setting labels.  More explicitly, 
with `\zref@labelbylist{refname}{listname}'.  But this is not a 
user/document command, the only one available of this kind is the 
mentioned undocumented `\zkvlabel'.  I took a look at its definition 
and, as far as I understand, its syntax is:

\zkvlabel{k=v options}{refname}

The accepted keys are: `list' (property list), `prop' (property to 
include), `delprop' (property to exclude), and `immediate' (a boolean, 
whether to write to .aux immediately).

Usually, you'd be either choosing the property list or the property, the 
hierarchical relation of them (the alist structure) is not specially 
meaningful.  In particular, when we are making the reference we can 
indeed specify the property we want to refer to, as you noted, but we 
have actually no way to infer the property list which generated the 
label.  In fact, only the properties are ever stored in the label.  So, 
if you set a label with `\zlabel', thus using the main list, you'll find 
(with bare bones default) in the aux file:

\zref@newlabel{sec:section-1}{\default{1}\page{1}}

We happen to "know" that's the main list, but we only ever see the 
properties.  And the thing is the properties actually included when 
setting a label can be changed on the fly, either by `\zkvlabel' or by a 
number of other internal mechanisms.  For example, you can add a 
property to a list locally, so that "main" may contain a further 
property within environment "foo".

That given, my suggestion would be to keep 
`LaTeX-zref-properties-(a?)list' a "flat" list of properties which can 
then be populated presumably basically with the properties of the "main" 
list, but potentially including other ones too, depending on need.  The 
bottom line is, when making the reference, we technically can't know 
what property list generated the label we are referring to.  We can 
presume "main", naturally, but even that may mean different things at 
different places.  Possibly, if you do choose to add support for 
`\zkvlabel', you may also want to keep a list of property lists.

> > Another related suggestion would be to have `zref-titleref.el' adding
> > "title" to `LaTeX-zref-properties-alist', which would be a common
> > need, I think.  For which there's also `\ztitleref' and
> > `\ztitlerefsetup'.
>
> I didn't get that far :-)

I assumed that. :-) It was just a suggestion of a module of general 
interest, to spare you some "manual groking".

> My idea was to have everything basic in zref.el, I think.

As you see fit.  It'd work just as well, I presume.  It just seemed 
atypical for "zref" to be in `TeX-active-styles' when `zref.sty' is 
never loaded.

> Thanks for your comments.  I'll send you the styles for more feedback
> when I have something working, just don't expect fast progress :-)

No hush at all, in your time.  And if you'd like to discuss any other 
points along the way, I remain at your disposal.

Thank you very much!

Best,
Gustavo.