Re: Issue 1110 in lilypond: Wrong octave of repetition chord with \relative and #{ #} syntax

[lilypond]

Comment #12 on issue 1110 by address@hidden: Wrong octave of repetition chord  
with \relative and #{ #} syntax
http://code.google.com/p/lilypond/issues/detail?id=1110

I have pretty much not slept at all this night because brooding over this.   
I'll spare you the dozen approaches I don't like all too well for various  
reasons.

The main point is that repeated chords and their original form another  
relativation problem in addition to the normal one.  We don't want to waste  
performance or create problems when we don't actually relativize.

The most straightforward approach I can think of is, when relativizing a  
music sequence, to do _two_ passes (or do one pass with two corresponding  
pitch state variables).  The first does the normal relativation while  
leaving repeated chords alone, the second carries over the last preceding  
absolute chord starting pitch to repeat chords.  A repeat chord in a  
relativized sequence that comes before any non-repeated chord is an error.

This makes the association between a repeat chord and its relativation  
reference different from the association for absolute pitches that is  
established in the parser.

But as demonstrated before, relativation is a sequential process and we  
can't guarantee that the sequence is compatible with a "hard link" between  
origin and repeat, even without the problem created by deep-copy.