Re: TimeSignature with note in denominator

[Aaron Hill]

On 2021-11-12 5:03 pm, David Kastrup wrote:
> Kieren MacMillan <kieren_macmillan@sympatico.ca> writes:
> > At that point, the only issue is to turn
> >
> >     \time #'(4 . "4.")
> >
> > into an number num and a *duration* (not number) denom… which again
> > doesn’t required parser-fiddling, correct?
>
> Utterly incorrect.  #'(4 . "4.") does not consult the LilyPond parser
> beyond the # and there is absolutely nothing that would magically turn
> "4." into a duration.  Nor should there be in my book.

Yeah, at this point, you'd have to manually write:

%%%%
\time #'(4 . #{ 4. #})
%%%%

And that's pretty ugly... so you might write a helper function:

%%%%
foo = #(define-scheme-function
 (numer denom) (number? ly:duration?)
 (cons numer denom))

\time \foo 4 4.
%%%%

It's a little better; but with proper parser support, a number-duration 
fraction format would be best:

%%%%
\time 4/4.
%%%%

That does presume, though, that TimeSignatureMusic would be refactored 
to support a non-numeric denominator.  At the moment, it requires 
numbers.  You could try to convert durations to numbers...

%%%%
timeFraction =
#(define-scheme-function
  (scalar duration)
  (number? ly:duration?)
  (let* ((moment (ly:duration-length duration))
         (numerator (ly:moment-main-numerator moment))
         (denominator (ly:moment-main-denominator moment)))
   (cons (* scalar numerator) denominator)))

\fixed c' {
  | \time \timeFraction 3 4. b4. a g
  | \time \timeFraction 2 2. b2 a4 g2 a4
}
%%%%

...but this conversion is inherently lossy.  The stencil procedure would 
have no idea what the original rhythmic denominator was.


-- Aaron Hill