Re: Auto_change_iterator no longer creates staff contexts itself. They are created in scheme. (issue 249970043 by address@hidden)

[thomasmorley65]

On 2015/06/28 00:17:58, Dan Eble wrote:
> On 2015/06/27 19:45:12, thomasmorley651 wrote:
> > bassStaffProperties and trebleStaffProperties are not really
documented,
> though
> > I'd call it more a documentation issue.
> ...
> > I vote for keeping them, although I think it's a very cumbersome
method to
> > specify which clefs the PianoStaff should use.

> If one follows the NR's suggestion to instantiate staves explicitly,
your
> example is transformed into something more lilypondish (below).
Removing these
> properties will make it easier for me to consolidate some code for
\autochange
> and \partcombine.

Let me clearify, I don't insist in keeping those properties, though I'd
like to keep the possibility to simply write \autochange { ... } _and_
to have the possibility to set the clefs in both staves.
The NR shows an example for \autochange { ... } and I think the
treble/bassStaffProperties were meant to set the clefs.

Following Davids suggestion, why not:

%% begin snippet

\version "2.19.22"

%% with patch applied

%% optional context-modifications working only, if contexts are not
instantiated
%% explicitly
autochange =
#(define-music-function (cm-1 cm-2 music)
  ((ly:context-mod? #{ \with { \clef treble} #})
   (ly:context-mod? #{ \with { \clef bass } #})
   ly:music?)
  (_i "Make voices that switch between staves automatically")
  (let ;; keep the contexts alive for the full duration
       ((skip (make-skip-music (make-duration-of-length
                                     (ly:music-length music)))))
    #{
      <<
        \context Staff = "up" $cm-1
          <<
          #(make-autochange-music music)
          \new Voice { #skip }
          >>
        \context Staff = "down" $cm-2
          \new Voice { #skip }
      >>
    #}))

%% TESTS

music = {
  g4 a b c'
  d'4 r a g
}

\autochange \music
\autochange \with { \clef alto } \music
\autochange \with { \clef alto } \with { \clef tenor }\music

%% end snippet

No need for treble/bassStaffProperties anymore

https://codereview.appspot.com/249970043/