Re: arranger.ly and lilypond 2.21+: error with the \note markup command

[Aaron Hill]

On 2021-01-15 4:10 pm, Thomas Morley wrote:
> Am Fr., 15. Jan. 2021 um 23:26 Uhr schrieb Stefano Troncaro
> <stefanotroncaro@gmail.com>:
> > Hi everyone,
> >
> > I started learning to use the spectacular arranger.ly library that was 
> > mentioned in the list a while ago.
> >
> > While most of it works great, I found that internally it sometimes 
> > uses the \note markup command, that changed between versions: in 2.20 
> > it requires an argument of type string, while from 2.21 onwards it 
> > requires an argument of type duration. This causes an error and makes 
> > it so that files that use arranger.ly do not compile on Lilypond 2.21 
> > onwards.
> >
> > I'm sure it'd be easy to patch. Is there an easy way to transform 
> > strings into durations?
>
> Iiuc, how about:
>
> %% from define-markup-commands
> #(use-modules (ice-9 regex))
>
> #(define-public log2
>   (let ((divisor (log 2)))
>     (lambda (z) (inexact->exact (/ (log z) divisor)))))
>
> #(define (parse-simple-duration duration-string)
>   "Parse the `duration-string', e.g. ''4..'' or ''breve.'',
> and return a (log dots) list."
>   (let ((match (regexp-exec (make-regexp 
> "(breve|longa|maxima|[0-9]+)(\\.*)")
>                             duration-string)))
>     (if (and match (string=? duration-string (match:substring match 
> 0)))
>         (let ((len (match:substring match 1))
>               (dots (match:substring match 2)))
>           (list (cond ((string=? len "breve") -1)
>                       ((string=? len "longa") -2)
>                       ((string=? len "maxima") -3)
>                       (else (log2 (string->number len))))
>                 (if dots (string-length dots) 0)))
>         (ly:error (_ "not a valid duration string: ~a") 
> duration-string))))
>
> %% and then:
>
> #(define (string->duration strg)
>   (apply ly:make-duration (parse-simple-duration strg)))
>
> %% test
> #(display-scheme-music (string->duration "16.."))
>
> Cheers,
>   Harm

Here's a back-compat patch that should allow \note to accept strings.  
Could be useful until arranger.ly is updated to use ly:durations in 
places where it relied on strings before.

%%%%
\version "2.22.0"

#(begin
  (define (duration-or-string? arg)
   (or (ly:duration? arg) (string? arg)))
  (define-markup-command
   (note layout props duration dir)
   (duration-or-string? number?)
   #:category music
   #:properties (note-by-number-markup)
   (if (string? duration)
    (set! duration
     (ly:parse-string-expression (ly:parser-clone) duration)))
   (note-by-number-markup layout props
                          (ly:duration-log duration)
                          (ly:duration-dot-count duration)
                          dir)))

\markup {
  \note { 8. } #DOWN \note "8." #DOWN
  \note { \longa*2/3 } #UP \note "\longa*2/3" #UP
}
%%%%


-- Aaron Hill