Setting the properties of a previously named context

[Jérémie Lumbroso]

Hello,

   In piano piece, where the range of the left hand far higher than
 what the staff can stand, I often need to operate a staff change. But
 When I do, the stem and notes of the bottom voice collide with those
 of the top-staff voices. It isn't a bug, but it requires of me to put
 a \stemUp each time I but the lower voice on the top staff (and a
 \stemDown on that voice), and then revert to \stemBoth when the voice
 returns to its normal staff. Since there are many of them, it becomes
 very tedious.

   Is there are a way to tell Lilypond to do this property changes
 each time I change staves? Or could it be possible to do something
 like this (pseudo code):

   toUp = {
      \translator Staff = "up"
      \property Voice.Stem = \set #'direction = #-1
      \property "voiceI".Stem \set #'direction = #1
   }

   toDown = {
      \translator Staff = "down"
      \property Voice.Stem = \revert #'direction
      \property "voiceI".Stem = \revert #'direction
   }

   
   What I'd like to know is if I can access the properties of a Voice,
 Staff, etc. by referring to its name as defined:
 
   \context Voice = "voiceI" { [...] }

   
-- 
Best regards,
 Jérémie                          mailto:address@hidden