Re: [Lilypond-auto] Issue 2990 in lilypond: \RemoveEmptyStaves in StaffGroup context crashes

[lilypond]

Comment #27 on issue 2990 by address@hidden: \RemoveEmptyStaves in StaffGroup  
context crashes
http://code.google.com/p/lilypond/issues/detail?id=2990

If you are talking on the level of "Grob can contain Grob arrays as  
properties", naturally recursive data structures are possible.  In that  
case, the algorithms have to be able to deal with them.  As far as I  
understand, however, we were talking about some hierarchical structure with  
a special role for "vertical axis groups".  If we want to maintain a level  
of integrity here, properties containing grobs and/or grob arrays are  
internals and should only be accessed by proper accessors.

Access them in any other way, and all bets are off.  I don't see that we  
have a reasonable description or definition of the structures making up  
vertical axis groups, and we don't have accessors for maintaining them.  If  
validity checks need to be an inherent part of the operation, the data  
structures may not be designed independently from the performance  
characteristics of the validity checks.