"StaffPartCombine" i.e. combine different *staves* on a single staff feature request

[Xavier Scheuer]

Dear LilyPond developers and users,
dear bug squad, could you add this feature request on the tracker?

Here is a feature request made on the French users mailing list.

It can be seen as a mix of "PartCombine" and "RemoveEmptyStaves".

Like in \partcombine , when the music is identical it is printed only
once (on the same one staff) but unlike \partcombine when the notes
differ they are not printed on different voices on the same staff,
but instead on _different staves_.


This would be a very useful for the many cases (in orchestral scores)
when the cellos and double basses play the same part or for example
when a single voice (e.g. "Violin I") split (div.):
people at the right-hand side of the stand play the upper part
and people at the left-hand side play the lower part.

Usually the "divisi staves" are joined thanks to a brace
(like a GrandStaff, sometimes like a StaffGroup, with spanbars).
Addition of "div." text at the separation and "unison" text
when "back to normal" would be nice too, as well as for example
the possibility to change the instrument names automatically
at these passages ("Vcl/Cb" vs "Vcl" and "Cb").
Sometimes (in existing published scores) the division is done
at a line break, sometimes not (in this case the "unison" part is
either printed on both separate staves, either the publisher uses
"repeat percent" measures).
Same for the "div. end", sometimes at a line break, sometimes not.
New parameters to define these desired settings would be appreciated.

And the "overkill feature" would be to have the same construction for
"VoicePartCombine" (aka current \partcombine) and "StaffPartCombine",
thus allowing to mix these different "combines" and for example to use
the same "notes files" but have different outputs for the conductor
and separate parts.

If it could handle more than two voices, that would be great,
as I have experienced 3 or 4 voices on different staves.

Many thanks for your consideration.

If you have questions, do not hesitate to ask.
Please do not forget to cc: Loïc and Jean-François as they asked for
this feature on the French users mailing list, so they could also say
how they would see this new feature work.

Cheers,
Xavier

-- 
Xavier Scheuer <address@hidden>