Re: Manipulating instrument names and staff group names

[Lukas-Fabian Moser]

Hi,
> > I also noticed that StaffCollection probably shouldn't have the 
> > Vertical_align_engraver, since this causes vertical spacing to be 
> > different. The original idea was that uncommenting in
> >
> > \version "2.23.4"
> >
> > bla = \repeat unfold 30 c'1
> >
> > <<
> >   \new Staff \bla
> > %{
> >   \new StaffCollection \with {
> >     \override StaffSymbol.color = #blue
> >     instrumentName = Test
> >   }
> > %}
> >   <<
> >     \new Staff \bla
> >     \new Staff \bla
> >   >>
> >   \new Staff \bla
> > >>
> >
> > shouldn't change spacing at all.
>
>
> Oh, was it? What is the point of StaffCollection then?
> I thought it was meant to group staves from a logical
> group of instruments. Don't you want to adjust the
> vertical spacing for that?

That would be open for debate. I was thinking mainly of the possibility 
of setting common properties for a group of staves (like the 
StaffSymbol.color in my example) without any layout side-effects. While 
this is merely a matter of convenience for Staff properties, it becomes 
necessary for instrumentNames: As I was (and maybe still am, but I have 
to get back to your email concerning this at a later point in time) 
thinking of providing the bracketed instrument names as a variant of 
instrumentName (maybe GroupName or CollectionName), it became necessary 
to group staves without automatic SystemStartDelimiter's.

Or, in short: To be able to group staves logically, not visually - where 
"logically" means "from the LilyPond perspective, not the musical 
perspective".

But it might well turn out that every reasonable use of StaffCollection 
also would deserve the vertical spacing implications of the 
Vertical_align_engraver.

It could also be made configurable:

visualGrouping = \with {
  \consists Vertical_align_engraver
}

\new StaffCollection \with { \visualGrouping }
<<
  % etc.
>>

Homework for me: Find out more about the actual job done by the 
Vertical_align_engraver.

> My spontaneous reaction would be to think that, while
> StaffGroup, ChoirStaff, GrandStaff and PianoStaff are
> four different ways of grouping staves with no
> conceptual hierarchy (even though I changed engraver-init.ly
> so it used \StaffGroup to conveniently define the others,
> but this does not end up as a relationship involving StaffGroup
> as any kind of parent), StaffCollection encompasses all
> four ways -- in OOP terms: a superclass with four
> distinct subclasses.

Yes, that's convincing, I think. The question might be if users are 
going to (or should) be aware that their StaffGroup's etc. are all 
different kinds of StaffCollection's.

Lukas