Re: music-function for ending TextSpanners sometimes fail for skip-events

[Thomas Morley]

Am Mi., 24. Okt. 2018 um 01:07 Uhr schrieb David Kastrup <address@hidden>:
>
> Thomas Morley <address@hidden> writes:
>
> > Am Di., 23. Okt. 2018 um 23:54 Uhr schrieb David Kastrup <address@hidden>:
> >
> >> So you should figure out what your comparison as equal is supposed to be
> >> doing in the first place.
> >
> > Yep, that's the culprit.
> >
> > So the question is how to find the last rhythmic event of a
> > music-expression and place <>\stopTextSpan right before it.
>
> Why wouldn't you just put \stopTextSpan on it?

The more or less single reason: because my initial posted function was
modeled after the built-in 'endSpanners' and there it's done this way.
Btw, in the line
                  (music-clone m 'span-direction STOP))
all music-properties are cloned as well.
Makes not much sense to me. P.e. why should a tweak for
bound-details.left.text of a TextSpanner be copied in the ending
script?
Right now I'm not aware of any property I would want to be copied into
the ending script.
Or did I overlook use-cases?
If not why not simply use a new constructed
          (make-event-chord
            (list (make-music
                    'what-ever-event
                    'span-direction
                    1)))
?

Back to the topic of this thread.
If someone's interested, I now come up with a code which was built after:
http://lsr.di.unimi.it/LSR/Item?id=83

\version "2.19.82"

%% after 'Adding extra fingering with scheme'
%% http://lsr.di.unimi.it/LSR/Item?id=83

endTextSpanners =
#(define-music-function (parser location music) (ly:music?)
   (let ((script #{ \stopTextSpan #})
         (do-it? #f)
         (last-seen #f))

     (define (append-script-at! my-music prop)
       (set! (ly:music-property my-music prop)
             (append (ly:music-property my-music prop)
                     (list (ly:music-deep-copy script))))
       my-music)
     (map-some-music
      (lambda (mus)
        (case (ly:music-property mus 'name)
          ((EventChord)
            (set! last-seen mus)
            (let* ((starts (extract-typed-music mus 'text-span-event)))
              (cond ((and (not do-it?) (pair? starts))
                     (set! do-it? #t)
                     mus)
                    ((and do-it? (pair? starts))
                     (append-script-at! mus 'elements))
                    (else mus))))
          ((NoteEvent RestEvent SkipEvent)
            (set! last-seen mus)
            (let* ((starts (extract-typed-music mus 'text-span-event)))
              (cond ((and (not do-it?) (pair? starts))
                     (set! do-it? #t)
                     mus)
                    ((and do-it? (pair? starts))
                     (append-script-at! mus 'articulations))
                    (else mus))))
          (else #f)))
      music)

      (case (ly:music-property last-seen 'name)
          ((EventChord)
           (append-script-at! last-seen 'elements))
          ((NoteEvent RestEvent SkipEvent)
           (append-script-at! last-seen 'articulations))
          (else #f))
      (set! do-it? #f)
      (set! last-seen #f)
      music))

 \endTextSpanners
   { c'4-3\startTextSpan <c' e' g'>\startTextSpan r s2 }

 \endTextSpanners
 {
   c'4 4\startTextSpan 4 4
   \repeat volta 2 {
     4\startTextSpan 4
     \tuplet 3/2 { 4\startTextSpan 4 <c' e'>4 }
   }
 }

Cheers,
  Harm