Re: Multiple repeat nested with alternative

[Hans Aberg]

On 13 Mar 2009, at 13:48, Valentin Villenave wrote:

> I'd happily add an official enhancement request for that, but I need a
> more precise and specific report (preferably with a minimal example).

Each \alternative might need a subsequence of the integer interval  
[1...n] indicated. For example, suppose someone wanted truly large  
repeat numbers, then it might be inconvenient to write them out all;  
just take 1-3,5,7-8,10 to illustrate the feature. Is there a lilyPond  
construct already that might express such a thing?

Then the feature that initiated this thread, the "hanging" last  
alternative, it strikes me might just be a way to indicate that it is  
empty. So a syntax like
  \repeat volta {A B}
    \alternative {C}
    \alternative {}
  \repeat volta {D E}
    \alternative {F}
    \alternative {}
  G H I J ...
might suffice for that. - It seems me that the number after "volta" is  
redundant, but might be kept as a check.

So combining these ideas, one might want to be able to write
  \repeat volta {A}
    \alternative 1,3 {B1}
    \alternative 2 {B2}
    \alternative 4-6 {B3}
    \alternative {}
    C
thus calling for
  A B1 A B2 A B1 A B3 A B3 A B3 A C
typeset as
       ______  ______  ______  __
      |1,3.  ||2.    ||4-6.  ||7.
| ... | ... :|| ... :|| ... :|| ... |
   A     B1      B2      B3      C
With no terminating hook on the last case (7). Here, C is just what  
follows. So if it is a part of a following \repeat volta ..., it  
should look like
       ______  ______  ______  __
      |1,3.  ||2.    ||4-6.  ||7.
| ... | ... :|| ... :|| ... :||: ... |
   A     B1      B2      B3      C
Also, the number 7 could written in and the number 2 could be dropped:
  \repeat volta 7 {A}
    \alternative 1,3 {B1}
    \alternative {B2}
    \alternative 4-6 {B3}
    \alternative 7 {}
    C
That is, if not numbers follows an \alternative, just the next unused  
number in the sequence 1, 2, 3, ... is filled in.

Would this not be backwards compatible with the current syntax and  
semantics for the cases it covers?

  Hans