Re:

[Aaron Hill]

On 2021-03-27 1:04 pm, Philippe ZELLER wrote:
> Dear lilypond fellow users,
> it sometimes occurs in barock music that only every other barline is
> visible, (see e.g. Haendel's Salomo, choir at the end of Act II ) or 
> that
> every other barline is printed in reduced size.(see e.g. Bach Mass in
> H-moll, nr 27 "dona nobis pacem" ).
> Is there a way to get this result in lilypond ?
>
> I first tried
> \set Score.barLineVisibility = #(every-nth-bar-number-visible 2)
> that I made up after an equivalent syntax for barNumber, but to no 
> avail.
> Maybe I didn't put it in the right context ?
>
> Finally I used a rather complicated procedure based on
> global = {
>       \repeat unfold 24 { s2. \once \override Staff.BarLine.transparent 
> =
> ##t  s2. \once \override Staff.BarLine.transparent = ##f }
>         }
> which works but is not fully compatible, for example it does not work 
> with
> multiMeasureRests.
>
> Many thanks in advance for your suggestions !

An engraver should be able to do the work:

%%%%
\version "2.22.0"

hideEveryOtherBarLine =
#(lambda (ctx)
  (define (bar-num)
   (ly:context-property ctx 'currentBarNumber))
  (make-engraver
   (acknowledgers
    ((bar-line-interface trans grob source)
     (if (= 0 (modulo (bar-num) 2))
      (ly:grob-set-property! grob 'transparent #t))))))

\new Staff
\with { \consists \hideEveryOtherBarLine }
\repeat unfold 10 { b'1 }
%%%%


-- Aaron Hill

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