Re: Refer to a staff relatively, not by name

[Urs Liska]

Hi Harm,

thanks for that suggestion.
Unfortunately it doesn't quite do what I need, and I don't really understand it.
But fortunately it gives quite a good clue how to ask more concretely.

It seems that functions/properties like
ly:context-id
ly:context-name 
provide information on the current context we're in.

a)
Is it possible to gather a list of all (Staff) contexts that are currently 
present?
b)
Is it possible to determine whether a given context is within a StaffGroup (or 
similar)?

With this information I hope it would be possible to identify the previous or 
next staff within a system in order to be able to "\change" to that Staff 
context.

Best
Urs


On Tue, 2 Apr 2013 01:20:00 +0200
Thomas Morley <address@hidden> wrote:

> \verson "2.17.15"
> 
> %%%% Helper functions, which simply print out the observed Music
> %%%% in a nice format:
> #(define (format-ctx engraver event)
>   (let* ((context (ly:translator-context engraver))
>          (ctx (ly:context-id context))
>          (ctx-name (ly:context-name context))
>          ;(mus (ly:event-property event 'music))
>          )
>     (ly:message "We are in \"~a\" with name \"~a\"\n\n" ctx-name ctx)
>   )
> )
> 
> %%%% The actual engraver definition: We just install a listener.
> 
> ctxInfo =
> #(list
>    (cons 'listeners
>     (list
>      (cons 'note-event format-ctx))))
> 
> \layout {
>   \context {
>     % I add this to the score, so all voices are caught. You can also only add
>     % the engraver to selected voices to get the statistics split down.
>     \Staff
>     \consists #ctxInfo
>   }
> }
> 
> \new ChoirStaff <<
>   \new Staff = "One" \with { instrumentName = "ctx 1" }
>     { \clef "treble_8" s1 * 6 }
> 
>   \new Staff = "Two" \with { instrumentName = "ctx 2" }
>     { \clef treble s1 * 6 }
> 
>   \new Staff = "Three" \with { instrumentName = "ctx 3" }
>     { \clef alto s1 * 6 }
> 
>   \new Staff = "Four" \with { instrumentName = "ctx 4" }
>     \relative f {
>       \clef bass c4 d e f
>       \change Staff = "Three" g' a b c
>       \change Staff = "Two" g a b c
>       \change Staff = "One" g, a b c
>       \change Staff = "Three" g a b c
>       \change Staff = "Four" g a b c
>     }
> >>