Re: beamExceptions and shorter notes

[Carl Sorensen]

On 12/29/10 10:29 AM, "Xavier Scheuer" <address@hidden> wrote:

> Hi Carl, LilyPond users,
> 
> In the doc NR 1.2.4 Beams > Setting automatic beam behavior
> (latest version: 2.13.44)
> under "How automatic beaming works", third point, it is said:
> 
>   ? if a beam-ending rule is defined in  beamExceptions  for a longer
>     beam-type, use it to determined the valid places where beams may
>     end, otherwise
>   [...]
> 
> 
> This is _not_ true for default beaming (i.e. 4/4), right?
> 
> In 4/4, there is a  beamExceptions  for 8th notes that combines beats
> 1,2 and 3,4, but this does not affect beaming rules for shorter
> beam-types (16th, ...) that are beamed according to  beamMoment
> (1 . 4) .
> How is it possible?

If you look at the default beaming rules defined in
scm/time-signature-settings.scm, you'll see that there is a beam ending rule
for (1 . 8) (4 4) followed by a beam ending rule for (1 . 12) (3 3 3 3).

This makes the 1/8 beam ending rule apply only to 1/8; for all shorter
beams, the 1/12 beam ending rule applies.

> 
> I ask this because we have a request on the French user mailing list
> to beam *in 2/4*  8th by 4  but without affecting shorter beam-types.
> And of course in this case if I use
> 
>   \time 2/4
>   \set Timing.beamExceptions =
>     #'(
>        (end .
>         (
>          ((1 . 8) . (4))
           ((1 . 12) . (3 3))
>         )))
> 
> then the beaming of shorter notes is determined by this and that's not
> what is wanted! (only 8th note should be beamed by measure, not shorter
> notes that should be beamed according to  beamMoment  (1 . 4)
> like in 4/4?!)
> 
> If you have another better solution to handle this situation, feel free!
> 

Whenever anybody has a question about setting beam rules, the first place to
look is probably scm/time-signature-settings.scm.

Thanks,

Carl