Re: Allowable values for output-attributes.id

On Mon, 2026-08-24 at 12:27 +0200, Thomas Morley wrote:
> Am So., 23. Aug. 2026 um 18:42 Uhr schrieb Richard Shann
> <[email protected]>:
> > 
> > Denemo has a version of Graham Percival's live-score.ily to
> > annotate
> > LilyPond's SVG output with line and column information for each
> > note
> > and rest in a score. With LilyPond version 2.26 this is not working
> > -
> > the SVG output contains <g id=""> instead of the line and column
> > information e.g. <g id="Note-12-10">. In the documentation it says
> > output-attributes.id can be set to symbols - in this case it is set
> > to
> > a procedure expecting a grob argument. It's not clear if that is an
> > acceptable value, but appears to have worked for the last ten
> > years.
> > This is the procedure definition and the override that is used
> > 
> > %%%%%%%%%%%%%%%%%%%%%%%%%
> > #(define (note-id grob)
> >    (let* ((origin (ly:input-file-line-char-column
> >                    (ly:event-property (ly:grob-property grob
> > 'cause) 'origin))))
> >   (string-concatenate
> >     (list
> >       "Note-"
> >       (ly:format "~a-~a"
> >         (cadr origin)
> >         (caddr origin))))))
> > 
> > \override NoteHead.output-attributes.id = #note-id
> > 
> > %%%%%%%%%%%%%%%%%%%%
> > The full include file is attached (after convert-ly) - it has a lot
> > of
> > redundant code as all Denemo needs is the location of notes and
> > rests
> > in the LilyPond score.
> > My question is, has something changed to make this fail?
> > 
> > Richard Shann
> 
> I seem to remember: in a nested list a sublist can not be set to a
> procedure while doing a grob override.
> If this is correct I wonder why that code ever worked.
> 
> Ofcourse you can use the _result_ of a procedure to construct said
> nested list:
> 
> #(define (note-id grob)
>   (let* ((origin (ly:input-file-line-char-column
>                    (ly:event-property (ly:grob-property grob 'cause)
> 'origin))))
>     (ly:format "Note-~a-~a"
>       (cadr origin)
>       (caddr origin))))
> 
> {
>   \override NoteHead.output-attributes =
>     #(grob-transformer 'output-attributes
>       (lambda (grob orig) (cons (cons 'id (note-id grob)) (or orig
> '()))))
> 
>   a1
>   \break
>   b1
> }
> 
> Does this work for you?

Yes, indeed it does - thank you very much.
I've noticed that I have another 2.26 upgrade problem the vibrato code
(wavy line above notes) which I think you wrote originally. It seems
this works with 2.26 but gets broken by applying convert-ly! But that's
for a separate thread.
Richard