Re: Patch to Axis_group_engraver + Scheme engraver for staff combining

[James Lowe]

Hello list,

On Wed, 6 Mar 2019 20:57:07 -0800, Saul Tobin <address@hidden> wrote:

> Hi all,
> 
> I posted some earlier versions of this Scheme engraver to the user list. It
> provides an intuitive user interface to control whether shared or separate
> staves are printed, and should work for combinations of 4 or more parts.
> The examples are in the tests.ly file attached, while the engraver code is
> in the divisi_engraver.ly file.
> 
> This engraver lives at the StaffGroup level and during process-music reads
> from one context property, then writes to keepAliveInterfaces of each child
> context. Because child contexts are evaluated first for process-music, in
> order to get this to work I needed to patch Axis_group_engraver so that it
> will wait to read keepAliveInterfaces and use the updated value.
> 
> Currently, Axis_group_engraver reads keepAliveInterfaces into an internal
> variable during process-music, then uses the stored value during
> acknowledge-grob. In the patched version, it waits to read
> keepAliveInterfaces during acknowledge-grob. Reading the property every
> grob is probably a performance hit, but I don't know how big.
> 
> Saul

I will shepherd this for Saul and put it in the patch review process.

James