Thank you Aaron for this explanation of the ly:prob-property! I see a
function like *ly:duration->string*, is there any way to "convert"
predicate types like ly:duration and number to markup?
Regards,
Martín.
Am Do., 17. Sept. 2020 um 01:23 Uhr schrieb Aaron Hill <
lilyp...@hillvisions.com>:
> On 2020-09-16 4:13 pm, Aaron Hill wrote:
> > On 2020-09-16 12:09 pm, Lukas-Fabian Moser wrote:
> >> I'm sure more knowledgeable people will be able to provide more
> >> insightful answers, but for what it's worth: Looking at
> >> lily/parser.yy, I see
> >>
> >> tempo_event:
> >> TEMPO steno_duration '=' tempo_range {
> >> $$ = MAKE_SYNTAX (tempo, @$, SCM_EOL, $2, $4);
> >> }
> >> | TEMPO text steno_duration '=' tempo_range {
> >> $$ = MAKE_SYNTAX (tempo, @$, $2, $3, $5);
> >> }
> >> | TEMPO text {
> >> $$ = MAKE_SYNTAX (tempo, @$, $2);
> >> } %prec ':'
> >> ;
> >>
> >> which I take to mean: The three forms
> >>
> >> * \tempo 4 = 96
> >> * \tempo Crazy 4 = 260-270
> >> * \tempo "Sluggishly slow"
> >>
> >> are hardcoded as variants into the parser. My guess is that this might
> >> be hard (or impossible) to accomplish in a music function.
> >
> > You just need to be a little creative. Consider:
> >
> > %%%%
> > \version "2.20.0"
> >
> > #(define (tempo? arg)
> > (and (ly:music? arg)
> > (not (null? (extract-typed-music arg 'tempo-change-event)))))
> >
> > doSomethingWithATempo =
> > #(define-void-function
> > (tempo)
> > (tempo?)
> > (set! tempo (first (extract-typed-music tempo 'tempo-change-event)))
> > (let ((tempo-unit (ly:prob-property tempo 'tempo-unit #f))
> > (metronome-count (ly:prob-property tempo 'metronome-count #f))
> > (text (ly:prob-property tempo 'text #f)))
> > (format #t "\nTempo: ~s"
> > (list (cons 'tempo-unit tempo-unit)
> > (cons 'metronome-count metronome-count)
> > (cons 'text text)))))
> >
> > \doSomethingWithATempo \tempo 4 = 60
> > \doSomethingWithATempo \tempo "Text" 4 = 60
> > \doSomethingWithATempo \tempo "Text"
> > %%%%
> >
> > ====
> > GNU LilyPond 2.20.0
> > Processing `tempo-function.ly'
> > Parsing...
> > Tempo: ((tempo-unit . #<Duration 4 >) (metronome-count . 60) (text .
> > #f))
> > Tempo: ((tempo-unit . #<Duration 4 >) (metronome-count . 60) (text .
> > "Text"))
> > Tempo: ((tempo-unit . #f) (metronome-count . #f) (text . "Text"))
> > Success: compilation successfully completed
> > ====
>
> Oops, I meant to include a test case for a tempo range:
>
> %%%%
> \doSomethingWithATempo \tempo "Text" 4 = 60-75
> %%%%
>
> ====
> Tempo: ((tempo-unit . #<Duration 4 >) (metronome-count 60 . 75) (text .
> "Text"))
> ====
>
> In summary, tempo-unit is ly:duration?; metronome-count is either
> number? or number-pair?; and text is markup?.
>
>
> -- Aaron Hill
>
>
--
www.martinrinconbotero.com
