Re: [Lilypond-auto] Issue 2584 in lilypond: please make partcombine merge slurs

[lilypond]

Comment #19 on issue 2584 by address@hidden: please make partcombine merge  
slurs
http://code.google.com/p/lilypond/issues/detail?id=2584

The part combiner is not actually to my opinion "reasonably sophisticated  
about spanners": for example, it does not combine voices if a slur from one  
voice but not another _ends_ on a note.  Part of its unwillingness to do  
this sort of combination might actually be due to the necessity of having  
to avoid simultaneous slurs.  If the part combiner used its own spanner-id  
on grobs supporting them, this might help.

I agree that the easiest fix for now (and reasonably justifiable) might be  
to conflate all slur starts and ends with identical spanner id.  I don't  
think this requires much extra work and, given that I was responsible for  
the previous "fix" introducing behavior that does not really play better  
with the part combiner, I am willing to do this.

However, there _does_ remain one question: what should we do if we have  
multiple slur starts differing in direction?  Either because one does not  
have a preferred direction, or because both have specified different  
directions?  In that case, it seems a bit weird to drop one slur.