Re: arbitrary repeat counter

[Jean Abou Samra]

Le 01/06/2022 à 18:04, Simon Bailey a écrit :
> On Wed, 1 Jun 2022 at 16:14, Jean Abou Samra <jean@abou-samra.fr> wrote:
> > > 1. What is the duration of a measure dependent on the current time signature?
> > In an engraver :-)
> >
> > (ly:context-property context 'measureLength)
> >
> > You can't get it in the music function, since timing is not
> > established at that point (just think that the time signature
> > could come from another element of a << >> construct, for
> > example).
> >
> > Remember, though, that the time signature might change
> > in the middle of the repeat. Thus it will be a bit
> > more reliable to actually acknowledge the PercentRepeatCount
> > grobs and increment a counter whenever you see one.
> I actually tried that and ran into scheme problems (incrementing a
> counter didn't seem to work).


What did not work? This is perfectly valid Scheme:

(set! count (1+ count))

In fact, it's in the code of my engraver.


> > > 2. How long is a given musical expression (in measures or beats)?
> > (ly:music-length your-music)
> I think I might use your engraver ;)  But I've definitely learnt more
> today. Thanks!


You're welcome. To be honest, and simplifying a bit, I had a
year of unsuccessful attempts to grasp Scheme before Urs'
Scheme tutorial made me learn as much of Scheme in 4 hours
as I had learnt in a year, then another year without that kind
of help to learn LilyPond internals, so if I've managed to write
something that is similarly turning a year into 4 hours for
you, I'm quite happy.

Best,
Jean