There's a fascinating library called Trellis which I really need to examine further one day: dataflow, automatic dependency handling, and more:

The Trellis "sees" what values your rules access, and thus knows what rules may need to be rerun when something changes -- not unlike the operation of a spreadsheet.But even more important, it also ensures that callbacks can't happen while code is "in the middle of something". Any action a rule takes that would cause a new event to fire is automatically deferred until all of the applicable rules have had a chance to respond to the event(s) in progress. And, if you try to access the value of a rule that hasn't been updated yet, it's automatically updated on-the-fly so that it reflects the current event in progress.No stale data. No race conditions. No callback management. That's what the Trellis gives you.