Re: Alleviating issue #34

Am Do., 1. Jan. 2026 um 17:59 Uhr schrieb Thomas Morley
<[email protected]>:
>
> Am Do., 1. Jan. 2026 um 14:37 Uhr schrieb Dan Eble <[email protected]>:
> >
> > On 2025-12-31 05:42, Thomas Morley wrote:
> > > At least for automatic repeats 'volta settings are entirely missing, why?
> >
> > Automatic repeats were enhanced to handle nested alternatives.  Manual
> > repeats were not.
> >
> > Volta_engraver gets information about the music structure from
> > volta-span-event:
> >
> >      void
> >      Volta_engraver::boot ()
> >      {
> >        ADD_ACKNOWLEDGER (bar_line);
> >        ADD_LISTENER (dal_segno);
> >        ADD_LISTENER (fine);
> >        ADD_LISTENER (volta_span);    //<<<<<<<<<<<<
> >      }
> >
> > For backward compatibility, Volta_engraver also reads the repeatCommands
> > context property and creates brackets that have a fixed relationship
> > with automatic brackets.  This is one reason why the "Manual repeat
> > marks" section of the NR begins with a cautionary note.
> >
> > I haven't reviewed your custom engraver, but an engraver concerned with
> > repeat structure might listen for some of these events in addition to
> > volta-span-event (from define-event-classes.scm):
> >
> >      (structural-event . (alternative-event
> >                           coda-mark-event
> >                           dal-segno-event
> >                           fine-event
> >                           section-event
> >                           segno-mark-event
> >                           volta-repeat-end-event
> >                           volta-repeat-start-event))
> >
> > Summary: Engravers handling repeat structure should listen for events.
> > If there is good reason to support the repeatCommands interface, they
> > should also read repeatCommands, but repeatCommands does not support the
> > same range of uses as automatic repeats.
> > --
> > Dan
> >
>
> Well, its not my engraver..., I may try to rewrite it, though.
>
> Thanks for the insights,
>   Harm

In 2.22.2 one could the following to cure #34 with repeats in a manual way:
%% example triggering issue 34
<<
  {
      \repeat volta 3 { \grace b8 b1 }
      \alternative { { \grace b8 c'1 } { \grace b8 d'1 } }
    e'1
  }
  {
      \repeat volta 3 { b1 } \alternative { c' d' } e'
  }
>>

%% manual cleared using \set repeatCommands = #'()
norC = \set repeatCommands = #'()

<<
  {
      \repeat volta 3 { \grace b8 b1 }
      \alternative { { \grace b8 c'1 } { \grace b8 d'1 } }
      e'1
  }
  {
      \repeat volta 3 { \norC b1 } \alternative { { \norC c' } { \norC d' } } e'
  }
>>

See attached image.

Basically, the engraver in question did this in an automatic way.
Alas, this does not work in current lilypond anymore.

If I try to redo the old engravers functionality looking at events, I
end up wishing to delete certain events from the music-stream.
Is this possible at all?
Or is there a better method for a workaround?

Cheers,
  Harm