[IMP-dev] Ordering among score_states (and other things)

[Daniel Russel <>]

I am ending up with various score states which have to be updated in  
the right order. Currently this requires that the user add them to the  
model in the right order and non-obvious things happen if this is not  
the case.  I think adding an iteration counter to the update call  
would make this simpler (and the change could be implemented without  
changing individual score states much).

Model maintains a counter which is incremented each time evaluate is  
called. It then calls ScoreState::update(int) for each score state  
passing the counter. This update is a method in the ScoreState base  
class which simply compares the passed counter to the stored counter  
and calls the existing update method if the counters are different.  
ScoreStates which depend on other score states can simply call update  
on their dependencies with the counter. Each ScoreState is updated  
exactly once and, unless there are circular dependencies, everything  
is updated before it is used. The same thing can be used for  
after_evaluate, although there is currently no need. With slightly  
more logic we could catch circular dependencies too.

Comments?