Re: alternate notes within a part

[David Wright]

On Sun 09 Jan 2022 at 23:36:41 (+0100), Valentin Petzel wrote:
> Am Sonntag, 9. Jänner 2022, 23:05:15 CET schrieb David Zelinsky:
> > I'm engraving a part that can be played either on cello or bassoon, but
> > with several differennces for short sections:  e.g. a clef change for
> > one and not the other; a different octave for a few measures; double
> > stops or not.
> > 
> > I want to have just one version of the source, assigned to a variable
> > (e.g. cello-bassoon-notes = {...} ), with the differences indicated by
> > short tagged sections (like \tag #'cello {...} \tag #'bassoon {...} ),
> > so that I can produce output for each instrument seperately from the
> > same source.
> > 
> > There seem to be a couple of problems using tags like this.  First, it's
> > kludgy because when the notes are parsed, Lilypond includes all notes
> > from both tagged parts, and complains about bar check failures.  That
> > doesn't really matter, since when the notes are used (as say
> > \keepWithTag #'cello) it all comes out right.  And I can avoid the
> > warnings if I tag full measures only.  But as I said, it's kludgy.
> > 
> > Worse is that a clef change in one tagged part affects all the
> > subsequent music.  And similarly, in \relative mode, the tags are
> > ignored when Lilypond determines the octave of following notes.
> > 
> > Is there a better way to accomplish what I'm trying to do?  Or do I
> > really just need to maintain completely separate versions for the two
> > instruments?
> 
> Much of what you’re describing should not happen. \keepWithTag and 
> \removeWithTag remove the music before it is parsed.
> 
> It is true that using tags with relative music can be a bit messy, as 
> depending on which part you remove the following music will change. You can 
> circumvent this by putting your tagged music in absolute mode.

I can't replicate that. AIUI the \music=\relative{…} has its pitches
baked in when the closing brace is read /on input/, regardless of
any tags read. When the music is set in \score{…}, the pitches can't
change.

OTOH any clefs in \music are only enacted as the music is typeset,
so they shouldn't be included in \music, but separately. Otherwise,
were a tagged section to finish in the wrong clef, you would have to
insert an extra clef but suppress its printing—not worth the hassle.

> Can you send us an example of your problems to see where it may come from?

Cheers,
David.

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