Re: strange appoggiatura behaviour

[James E. Bailey]

Am 28.08.2008 um 01:38 schrieb Reinhold Kainhofer:

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> Am Mittwoch, 27. August 2008 schrieb Daniel Hulme:
> > On Wed, Aug 27, 2008 at 10:32:31PM +0200, Reinhold Kainhofer wrote:
> > > Am Mittwoch, 27. August 2008 schrieb James E. Bailey:
> > > > Oddly, in the attached code, if the appoggiatura is commented out,
> > > > then the stems follow how they're supposed to. Is this a bug or a
> > > > super-special feature of graceMusic that I just didn't know about?
> > >
> > > It seems that the grace note commands are yet another example of a
> > > command that messes up ooiceOne/voiceTwo settings (by simply  
> > > reverting
> > > the stem direction instead of restoring the previous value). Other
> > > examples I'm aware of are the cue commands.
> >
> > I'm glad someone has pointed this out, as it explains some previously
> > mysterious behaviour. As I use Lilypond mostly for typesetting drum
> > parts, pretty much every piece has grace notes and multiple voices.
> >
> > If someone who knows could point me towards the appropriate bit of  
> > code,
> > it would give me great pleasure to cook up a patch and send to - 
> > devel.
>
> Unfortunately it's not that simple to even understand where the  
> problem
> happens. I looked at the internal music expression with and without  
> the
> \voiceOne and there is no explicit stem direction change after the  
> grace
> note. So it is not a problem of e.g. make-voice-props-revert, but  
> rather a
> by-product of the processing!
>
> I noticed that my initial assumption was wrong that the grace  
> command reverts
> the stem direction. If you add any note or rest between the  
> \voiceOne and the
> \appoggiatura, everything will work just fine. Apparently the stem  
> change by
> \voiceOne is never recorded, because that seems to happen only on  
> notes/rests
> and the first note after the \voiceOne is the grace note, which has  
> its stem
> explicitly set to #UP.
> Thus, lilypond never realizes that the stem direction should be set  
> to #UP for
> all notes.
>
> Please note that other settings of \voiceOne are correctly applied  
> (like the
> rest position)
>
> I suppose this is a bug in Lilypond, which can be summarized as:
>     "\voiceOne immediately before a grace command does not properly  
> set
>      the stem direction".

At the very least, a known issue, since the problem is adequately  
solved by adding \voiceOne immediately after the grace command.