Re: Automatically unfold percent and tremolo repeats in MIDI output. (issue 769) (issue 40720060)

[Devon Schudy]

Unfolding during iteration doesn't extend well to voltas, because it
changes their length. Even if the length is updated, the old length
has already been used by the parent iterator to compute moments for
subsequent events. So unless this can be changed, unfolding will have
to be done earlier, on music expressions. Unfortunately I think this
means unfold settings must come from the output def instead of the
context, so they can't be changed locally. This is not looking good
for voltas.

Keith wrote:
> I think we need the tremolo-type property to hold the 32 from input c2:32

On TremoloEvent, yes. But do we need it on TremoloRepeatedMusic? I
suppose it might be handy for tweaking.

dak wrote:
> This does not belong in the Repeated_music class.  It's not a property
> of the music, but of iteration.

Repeated_music isn't a music class — it should really be called
something like Repeat_utilities. (And it could be a namespace, not a
class.)

> I'm not happy with the hardcoding of midi, but until we can write
> \new Staff \with { \midi { repeatTypes = #'(volta-repeated-music } }
> namely until context mods can get more discriminatory, we are probably
> stuck with it.

\score { ... \layout { \context { \Score unfoldRepeats = #'(tremolo volta) } } }
is a tolerable way to specify non-midi unfolding.

> That condition does not agree with the current implementation of
> unfold-repeats-fully [...] Seems like I should push a fix to that...

Or export Repeated_music::unfolded_music to Scheme and call it. This
part of the patch doesn't depend on tremolo cleanup or anything else.