Re: Best practice for parts with varying number of staves

[Keith OHara]

Urs Liska <ul <at> openlilylib.org> writes:

> Some parts vary the number of staves along the way (for example the
> violas are written on one up to four(!) staves). 

> b)
> I could add some 'padding' empty measures around each additional staff
> to ensure that when the music starts in the middle of a system there are
> empty measures available from the start of the system.
> -> This might work but seems awkward in the entering phase because I
> have to start/stop the additional staves at arbitrary points. 

If you want the traditional output with staves filling whole lines, then
I think you will want to use your plan b or plan c.  The 'padding' can
be of a length convenient for you, maybe the length of music you would
assign to one variable, and LilyPond will quickly skip over the music
that she does not need to lay out.

1) In cases of divisi, where the violas split into two parts and rejoin,
you could 

a) allow temporary staves to start and stop mid-line, which can be very
clear with the right labels and span-bars, or

b) for the traditional way where temporary staves fill whole lines,
include the music where violas are in unison in *both* Staff contexts
(maybe by including your variable holding their music to the next
rehearsal mark in the sequence for both Staff contexts) and tell LilyPond
she may consider the shared segment of music on the temporary staff
as-if-empty for purposes of \RemoveEmptyStaves.
<http://lists.gnu.org/archive/html/lilypond-user/2012-12/msg00059.html>
<http://lists.gnu.org/archive/html/lilypond-user-fr/2012-08/msg00050.html>

2) In cases where layers of violas come and go (like in "Thus Spoke
Zarathustra") then you will need multi-measure rests in the individual
parts, so you will want to write R1*456 or #(mmrest-of-length firstViolaQ)
for the player that sits quietly, and use RemoveEmptyStaves as usual.