Olivier Biot <[email protected]> writes:
> On Sat, Mar 9, 2013 at 12:20 AM, David Kastrup <[email protected]> wrote:
[...]
> > Personally I think that
> >
> > c'' \relative { ... }
> >
> > is more intuitive than
> >
> > \relative c'' { ... }
>
>
> music functions don't look back into context, and if they are in
> variables, they don't even _have_ context.
>
> I wasn't aware of this - I took for granted that this was needed to
> keep state. Probably \relative does this under the hood.
It walks through the music, calling every expression's
to-relative-callback if available and uses a default conversion if not.
The relative-callback of the resulting expression is transparent, so the
contents of an inner \relative are invisible to an outer one.
> Considering that \relative came as a feature after the core LilyPond
> was written, it makes sense to me now.
No idea about that. I moved \relative from the parser into a music
function sometime in 2.15. I don't know about its previous history.
> The default LilyPond pitch. If you personally think that could be
> made to work, I am looking forward to your sample implementation.
>
> Well, since there is no state information available as you stated,
> this is going to be tricky indeed, unless we add another command that
> adds some context the same way \relative computes the closest pitch to
> transform a relative pitch expression into absolute pitches.
I don't understand, but presumably we are working from different
assumptions.
> Or actually even a coherent and comprehensive human-readable
> definition that could be placed in the manual and would make it
> possible for a user to predict LilyPond's behavior without
> experimenting.
>
> I see that as less of a problem. I'd read c'' \relative { e g b } as
> c'', then after this a series of relative pitches starting from the
> last known pitch (or c' - the default LilyPond pitch).
This needs a coherent and comprehensive definition of "last known pitch"
and a definition when "or c'" is going to kick in. So far this is
mostly hand-waving, and I am quite skeptical it can be taken beyond that
stage.
> Thinking of which, I believe I am struggling with "music entry
> notation" versus "music storage": writing in relative pitch is often
> easier for note entry, but absolute pitches are IMHO better suited for
> storing music.
The result of \relative _is_ stored as absolute pitches. It is only
very occasionally that pitches are stored as relative, and then LilyPond
does not know about it. Example:
xxx = { c d e f g }
Relative or absolute? You can equally well now write
\new Voice { \relative c' \xxx }
or
\new Voice { \xxx }
or even both. So in _this_ case, pitches have been stored as absolute
as well as relative in the same variable. But if you write
xxx = \relative c' { c d e f g }
they are stored as absolute pitches, period. No amount of \relative
placed around \xxx will change its pitches any more.
--
David Kastrup
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