Re: \stopStaff \startStaff bug

[Kieren MacMillan]

Hi David (et al.),

>> In that case, the NoteHead one has no effect, because \once applies to
>> the next time step only, and the next time step is for a grace note
>> another voice.
> 
> The recovery action of \once should likely occur after the next _local_
> timestep.
> 
>> Do they occur after?  In that case, the TimeSignature one has no
>> effect, because the TimeSignature grob was created before the graces.
>> The latter is the currently chosen interpretation.
> 
> With that interpretation, \once \override Staff.NoteHead.color would
> color _all_ grace notes.  An alternative would be to try to involve
> \context ... constructs in the grace fixup decisions, in which case
> NoteHead.color and Staff.NoteHead.color would lead to different timings
> of the result.
> 
>> So what do you do for an arbitrary \once \override? Especially if
>> there is a Scheme engraver that might decide to create this grob at
>> any time?
> 
> \once \override is not a grob.

It appears that David is saying exactly what I’m suggesting [separating grobs 
from zero-duration events, eliminating context-bleed, etc.], the only exception 
being the order of operations (pre-grace or post-grace). If David’s approach 
*does* “map well into code intended for computers”, I could care less about the 
actual order of operations that Lilypond takes.

Cheers,
Kieren.