Re: Strange behaviour with unknown alternativeNumberingStyle

[Dan Eble]

On Dec 30, 2022, at 12:10, Thomas Morley <thomasmorley65@gmail.com> wrote:
> 
> Hi all,
> 
> please have a look at:
> 
> \version "2.25.0"
> 
> {
>  \override Score.BarNumber.break-visibility = ##(#f #t #t)
> %  \set Score.alternativeNumberingStyle = #'whatever
>  b1
>  \repeat volta 2 { c' c' }
>  \alternative { d' e' }
>  f'
> }
> 
> As soon as the style-setting is uncommented it behaves like
>  \set Score.alternativeNumberingStyle = #'number
> shouldn't an unknown style behave like the default '()?

I don't see documentation or regression tests for anything beyond 'number and 
'numbers-with-letters.

Since https://gitlab.com/lilypond/lilypond/-/merge_requests/594#note_477121479, 
Timing_translator chooses the numbers and Bar_number_engraver formats them.  
Any value of "alternativeNumberingStyle" causes Timing_translator to use the 
alternative numbering scheme common to both of those styles.

> tl;dr
> This probably prevents me defining a knew style
> with a custom engraver
> as fix for lsr-snippet 1080 "Incrementing bar numbers in volta
> repeats"
> https://lsr.di.unimi.it/LSR/Item?id=1080

From the description: "Here is a hack that increments the currentBarNumber 
property whenever volta repeats occur.  It also offers basic (though limited) 
support for alternatives."

Do you need a new value for alternativeNumberingStyle?  If you want the 
behavior arising from leaving alternativeNumberingStyle unset, why not leave it 
unset and let your custom engraver do the rest?

Besides, the snippet's numbering scheme seems oriented toward the volte in 
general rather than the alternatives.  It isn't clearly a new kind of 
alternative numbering.
— 
Dan