Re: \once \set Timing.defaultBarType fails!

[Mats Bengtsson]

Han-Wen Nienhuys wrote:
> Mats Bengtsson escreveu:
>   
> > Why do the bar lines disappear completely in the following example?
> >
> > \version "2.11.15"
> > \relative{
> > c1 | \once \set Timing.defaultBarType = ":"  c1 | c1 |
> > }
> >
> > If you remove the \once, it works as expected and \once \set works
> > correctly
> > in other situations.
> >     
>
> wild guess: becuase defaultBarType is defined in Score, not Global.
> \once restores the value from the enclosing context.
>   
It seems that you are right. Adding
\layout{
 \context{
   \Global
   defaultBarType = "|"
 }
}
results in solid bar lines. Still, it seems that \once \set 
Timing.defaultBar isn't
useful, since a \set Timing.defaultBar that appears at a bar line isn't 
noticed
until the end of the next measure, i.e. you need at least one note 
between the
setting and the bar line. Since this note will "consume" the  \once, 
neither of
\once \set Timing.defaultBar = "dashed" c1 |
or
c1 \once \set Timing.defaultBar = "dashed" |
will work. Of course, a better solution in this specific case is 
probably to
use \bar "dashed" instead.

However, I'm really confused by your statement that \once restores the value
from the *enclosing* set. I had the impression that \set and \revert 
stored values
on a stack that's specific to the corresponding context and that \once 
\set was
equivalent to \push ... \pull, but from your answer it seems that this 
isn't the case.

  /Mats