Re: How to extract the current time signature

[Urs Liska]

[Reviving a pretty ancient thread]

Hi Abraham and Harm (and others),

Am 22.01.15 um 14:17 schrieb tisimst:
> Harm,
>
>
> Thomas Morley-2 wrote
> > Maybe:
> >
> > \version "2.19.15"
> >
> > printTimeSignatureFraction =
> > \applyContext #(lambda (ctx)
> >    (let* ((context
> >             (ly:context-property-where-defined ctx 'timeSignatureFraction))
> >           (time-sig-frac
> >             (ly:context-property context 'timeSignatureFraction)))
> >    (display time-sig-frac)))
> >
> > \relative c' {
> >      \time 3/2
> >      \printTimeSignatureFraction % => (3 . 2)
> >      c''1
> >          \compoundMeter #'((1 4) (3 8))
> >      \printTimeSignatureFraction % => (5 . 8) !!
> >          \repeat unfold 5 c8 \repeat unfold 10 c16
> > }
> >
> > Though the compound TimeSig will return "summarized"
> >
> > Cheers,
> >    Harm
> That works great! Thanks so much for your help. Perhaps I should have
> mentioned it in the original post, but I'd like to be able to use the values
> in time-sig-frac to automatically make a MultiMeasureRest with the duration
> of the full measure, but when I attempt to do so, nothing gets added to my
> score. Here's my latest and greatest:
>
> %<------------------------------
>
> \version "2.18.2"
>
> autoMMR =
> \applyContext #(lambda (ctx)
>    (let* ((context
>             (ly:context-property-where-defined ctx 'timeSignatureFraction))
>           (time-sig-frac
>             (ly:context-property context 'timeSignatureFraction))
>           (num (car time-sig-frac))
>           (den (cdr time-sig-frac)))
>      (make-music 'MultiMeasureRestMusic
>         'duration
>         (ly:make-duration 0 0 num den)
>         'articulations
>         '())
> ))
>
> \relative c' {
>    \time 3/2
>    \autoMMR
>    c'1.
>
>    \compoundMeter #'((1 4)(3 8))
>    \autoMMR
>    \repeat unfold 5 c8 \repeat unfold 10 c16
> }
>
> %<------------------------------
>
> I know that applyContext creates its own "(make-music ..." block, so maybe
> there's some scoping issue I'm not aware of. Any further help would be
> greatly appreciated!
>
> -Abraham
I've just run into the very same issue (also trying to create a MMR for 
the current measure's duration.

Looking at the code examples above I'm pretty sure the problem is not a 
"scoping" but a "timing" issue - I think \applyContext performs the 
context lookup long after the MMR has been created. This seems pretty 
clear because at the time a music-function is interpreted (and the 
duration would be needed to create the MMR) it is not clear where this 
music will end up. Consider the case when you define this in a variable 
which you'll then reuse multiple times (possibly starting at different 
moments in a measure or wrapped in \scaleDurations or \tuplet-s).

So while I get why this doesn't work that way, is there any chance to 
create a one-measure MMR from a music-function?

My use case is that I want to align an arbitrary markup (or music of 
arbitrary length) with a measure by (ab)using the MMR, I don't want to 
require a duration argument to the music function, and making it 
optional seems to interfere with the rest of the function signature.

Urs