Re: ly:grob-system not working as expected

[David Kastrup]

Mark Polesky <address@hidden> writes:

> Compiling this file displays "#<Grob System >" on the stdout:
>
>
> {
>   \tweak before-line-breaking
>     #(lambda (grob)
>        (let* ((NoteColumn  (ly:grob-parent grob X)) 
>               (PaperColumn (ly:grob-parent NoteColumn X)) 
>               (System      (ly:grob-parent PaperColumn X)))
>        (display System)))
>   c'' 
> }
>
> I expected this to do the same, but instead it prints "()".
>
> {
>   \tweak before-line-breaking
>     #(lambda (grob) (display (ly:grob-system grob)))
>   c'' 
> }
>
> Am I missing something?  Or is ly:grob-system broken?

ly:grob-system only returns the system after is has been set in the
PaperColumn which is after line breaking.  What you see as #<Grob
System > above is a single system encompassing the entire score.

-- 
David Kastrup