Re: Lyric extenders in/out of alternatives

[Dan Eble]

On Oct 4, 2021, at 12:44, Lukas-Fabian Moser <lfm@gmx.de> wrote:
> 
>>> Of course, the ideal solution would be a possibility to tell the Lyrics 
>>> context that it should "take" the second alternative and make it skip the 
>>> first alternative automatically (and suspend the LyricExtender along the 
>>> way). But my feeling is that this would be not so easy to implement.
>> 
>> Probably doable, and probably a fair bit of work.
> 
> I'd basically be interested in trying to understand the mechanics involved, 
> but seeing as term started today at our university, I'm sceptical I can spend 
> serious time on this before Christmas break. (And there's a fair chance it 
> would be above my head anyway.)

Volta_specced_music_iterator emits VoltaSpanEvents carrying i,j,k at the start 
and end of \volta i,j,k {}.  I expect that Lyric_combine_music_iterator could 
register for these events and use them to ignore notes that do not apply to the 
volta of interest.

You would want a way to indicate in the ly code that a span of lyrics should be 
set to a specific volta of the music.  The existing stanza number feature seems 
obvious, but it would be limiting.  (Examples: a partly through-composed 
arrangement with 2 stanzas per volta; a transcription of stanzas 1, 5, and 9 of 
a source in a situation where renumbering is undesirable)

I am asking myself, "Why not use \volta for that?" and I don't have an answer 
yet.
— 
Dan