Re: RFC and help at MR 2256

[Thomas Morley]

Am So., 11. Feb. 2024 um 13:51 Uhr schrieb Jean Abou Samra <jean@abou-samra.fr>:
>
> > Alas, as soon as the relevant engravers are moved to another context,
> > which is a common use case, I get an error:
> >
> > programming error: cyclic dependency: calculation-in-progress
> > encountered for AgogicLineSpanner.vertical-skylines
> >
> > and the graphical output is wrong.
> > Again, this does not happen at score-level.
> > Example-code to trigger it at #2256
> >
> > I've no clue how to proceed. Every hint is very welcome.
>
> I don't really have the time to investigate, but have you tried
>
> #(ly:set-option 'debug-property-callbacks)
>
> ? It should print a stack of the callbacks showing the cyclic dependency.
>

It prints

backtrace:
  0: AgogicLineSpanner.Y-offset (#<procedure
ly:side-position-interface::y-aligned-side (_ #:optional _)>)
  1: AgogicLineSpanner.vertical-skylines (#<procedure
ly:grob::vertical-skylines-from-element-stencils (_)>)
  2: VerticalAxisGroup.vertical-skylines (#<procedure
ly:hara-kiri-group-spanner::calc-skylines (_)>)

Not sure what exactly that means and how to solve the problem.
Maybe I have an idea (about 'side-support-elements).
I'll try and report back.

Thanks,
  Harm