New way of creating repeats

[Rune Zedeler]

This is a suggestion for a new, and IMHO very useful feature of
LilyPond.
Creating repeated sections in lily is currently not flexible enough.
I.e. If one want's

||: c d e f |  %  |  %  :||  %  |  %  |.

Then it is currently not possible.
Further more tying big (i.e. 5 note) chords together is hell because one
has to repeat all the notes in the chord.
Finally, in rhytmic music, it is common to omit some repeated chords.
So that instead of

  ___________
 |   |   |   |
 |   |   |   |
O   O   O   O
O   O   O   O
O   O   O   O

(same chord)

One wants

  ___________
 |   |   |   |
 |   |   |   |
O            
O            
O            

or

  ___________
 |   |   |   |
 |   |   |   |
O    /   /   /
O   /   /   /
O            

(no heads or a single slash head on the repeated notes)

I suggest a new style repeat:
In a sequential music, "x" means the previous note-containing element in
the sequence - and i.e "x4" means the same but with a duration of 4
(only makes sence if the previous element is a chord).
The default is to simply "unfold" the x'es, so that i.e.

{ { c4 d8 e } x x x }
gives
{ {c4 d8 e }{c4 d8 e }{c4 d8 e }{c4 d8 e } }

and

{ < c4. e g b >~x8 x8~x4 x }
gives
{ < c4. e g b >~< c8 e g b > < c8 e g b >~< c4 e g b > < c4 e g b > }

But it should be possible to tweak the repeated sections, i.e. having a
property x-repeat-style which could have values like

unfold, invisible, slash, percent.

Another great advantage of this is that in the SCORE (containing all
voices) one typically wants the notes to be written completely out while
in the INSTRUMENT PARTS one want's repeated chords to be squashed (to
make it easier for a musician to see when the chords change).
Currently this is not possible - except that you can type the voice
twice. With the new scheme, this would be easy - just change a single
property.

As you all know I am busy now, but in the summer I'll be active again
(in a producing not just a commenting way). Until then I would like
comments on this idea - surely there must be somehing that I have
overlooked.


-Rune