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

[David Wright]

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.