Re: macro for \once\override

[Aaron Hill]

On 2020-08-29 6:37 am, David Kastrup wrote:
> Aaron Hill <lilypond@hillvisions.com> writes:
>
> > On 2020-08-29 5:23 am, David Kastrup wrote:
> > > Wols Lists <antlists@youngman.org.uk> writes:
> > >
> > > > On 29/08/20 05:45, Werner LEMBERG wrote:
> > > > >       \once \override FretBoard.size = #'1.0
> > > > >       \once \override FretBoard.fret-diagram-details.barre-type =
> > > > > #'straight
> > > > >       \once \override FretBoard.fret-diagram-details.dot-color =
> > > > > #'black
> > > > >       \once \override FretBoard.fret-diagram-details.finger-code =
> > > > > #'below-string
> > > > >       c'
> > > > Unfortunately this might well require re-writing the parser, but it
> > > > struck me it might be a nice idea to nick an idea from other object
> > > > oriented languages as follows ...
> > > >     \once \override FretBoard.size = #'1.0
> > > >     \once \override \using FretBoard.fret-diagram-details {
> > > >         .barre-type = #'straight
> > > >         .dot-color = #'black
> > > >         .finger-code = #'below-string
> > > >     }
> > > >     c'
> > > What's wrong with
> > >   \once \override FretBoard.fret-diagram-details =
> > >     #'((barre-type . straight)
> > >        (dot-color . black)
> > >        (finger-code . below-string))
> > > I mean, I am as proud as anybody that separate subproperty overrides
> > > don't cause LilyPond to go down in flames any more, but this is an
> > > alist, after all.
> >
> > In my testing, that overwrites any existing overrides on the
> > fret-diagram-details property, so it is not quite the same thing.
>
> The only preexisting fret-diagram-details entry according to the
> internals guide is finger-code , and that one's in there.

Apologies for not being clearer.  I was not talking about that specific 
bit of code, rather using that construct in the larger example that 
Werner posted.  In the snippet, some elements of the 
fret-diagram-details property were \overridden earlier and those would 
not be persisted if you swap out the entire alist.


-- Aaron Hill