Re: Understanding how \tag works in \relative pitched music

[David Wright]

On Fri 04 Aug 2017 at 23:51:49 (-0500), Guy Stalnaker wrote:
> So it's an Order of Operations issue.

Unfortunately, your capitalisation indicates you haven't really
understood the implications of what I wrote.

> Pitches entered using \relative are
> first converted to absolute then the selection using \tag conditional.

But the conversion is effectively a lexical one, and is demonstrated
by the attached which is your example in absolute notation. If the
"\absolute evangelists" were to persuade the maintainers to abolish
\relative, a text editor could be persuaded to do the job. As things
are,   $ ly "rel2abs" -o abs.ly rel.ly
does the job.

> Which suggests that \tag used with \relative will never work.

They both work perfectly. The problem is that you thought you
could use \relative to do something semantic. There's a cure.
-When you use \relative, look at the pitches only, and treat the
source in strict lexical order in a single pass.
-When you are designing your \tag structure, imagine that all the
"\relative [optional-pitch]" occurrences have evaporated, leaving
behind just their { } and << >> constructs.

You know, sometimes I think it might have been wiser to go the
whole hog and treat relative/absolute/fixed in the same way
as \language is. The only thing I can see that you lose is their
ability to be nested. I wonder how many people rely on that.

> On Aug 4, 2017 10:45 PM, "David Wright" <address@hidden> wrote:
> 
> > On Fri 04 Aug 2017 at 15:41:34 (-0500), Guy Stalnaker wrote:
> > > All,
> > >
> > > Why is this output being created? I would expect to get exactly the same
> > > pitches on all three staffs, but since not, my expectations are obviously
> > > wrong.
> > >
> > > %% SNIPPET %%
> > > ​straightMusic = \relative c' {
> > >   a2 _\markup { no tag, relative pitch } cis4 e |
> > >   fis1 |
> > > }
> > >
> > > clarinetOneMusic = \relative c' {
> > >   \set Score.markFormatter = #format-mark-box-numbers
> > >   \tag #'mark { \mark \default a2 _\markup { tag mark, relative pitch }
> > > cis4 e | }
> > >   \tag #'no-mark { a2 _\markup { tag no-mark, relative pitch } cis4 e | }
> > >   fis1 |
> > > }
> >
> > Here are the pitches you have entered:
> >
> > straightMusic = \relative c' { a2 cis4 e fis1 }
> >
> > clarinetOneMusic = \relative c' { a2 cis4 e a2 cis4 e fis1 }
> >
> > These pitches are interpreted during _input_ of the source and
> > become absolute pitches as they are read. They are now absolute
> > and stay that way.
> >
> > You have then selected a different set of notes (each with an absolute
> > pitch) for each staff by using tags, and then transposed them.
> >
> > In other words, \relative { … } is a one-shot, immediate input process
> > for making melodic input more convenient (for those of us who like it).
> >
> > Bear in mind that if \relative { … } contains notes that are already
> > absolute, eg,
> > \relative { … \absolute { A } … \transpose { T } … \relative { R } … }
> > the outer \relative does not reprocess A, T and R because they're
> > already absolute. (R is processed by the inner \relative first.)
> > Only the "…" notes are processed by the outer \relative.

Cheers,
David.

op-abs.ly
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