Re: Metronome mark not aligning correctly

[Jean Abou Samra]

Le 06/11/2021 à 14:47, Kieren MacMillan a écrit :
> [...]
> Is there some gain to be had by considering the three related concepts — 
> “context pushing”, cross-staff items, and part-combining — together, to see 
> where a single mechanism might help all three? Put another (OOP-ish) way: Are 
> cross-staffing and part-combining instances of a context-pushing class?


Almost, but not quite. Having separate contexts
is inflexible because you cannot link them in other
ways, e.g., you cannot have a slur crossing two Voices.
While this is hampering the part combiner, I am not
sure "pushing to contexts" will help in that case:
the problem is really "merging" stuff (like
making one note column for notes from the two
or, let's hope, n parts). The vague idea I had
in mind was the capability of stopping and starting
engravers midway in the course of the lifetime of
a context. An a due passage would be handled by
stopping the Stem_engravers, etc. in Voice and
starting one in a higher context encompassing the
two or n Voices.

That may in turn help for cross-staff, but that
other problem also requires more thought with
respect to the context hierarchy (contexts with
several parents? what can we invent?).



> That was my [totally naïve] instinct, too (cf. 
> https://lists.gnu.org/archive/html/lilypond-user/2021-10/msg00436.html). I look 
> forward to seeing where this discussion leads!


By all means help if you can, but don't
hold your breathe for it. All of what I
say here remains totally sketchy and handwaving
for the time being, and may turn out to be
entirely ill-advised or irrelevant. I'll be
happy if people start experimenting. The energy
that I can personally dedicate to LilyPond is
currently absorbed by trying to understand
purity and to refactor unpure/pure containers,
so I won't be working on this domain anytime soon.

Best,
Jean