question

The rule needs to return 0 to allow the traveller to pass, and 1 if the barrier is in place. So you need to track the barrier allocation somehow using a list, label or other attribute.

So then the question is how to reference the barrier attribute in the rule. Well at the moment: "If you want to have a different rule for each barrier, then you need to add a rule for each barrier." Then you will hard code your barrier reference into the rule using a Model.find("myBarrierAsAString/path") so that you can find out what is the current allocation. So you may be able to specify a rule generically that could be written once and used for hundreds of barriers in your model if the reference was passed in, but you won't be able to do that currently - you need to create a rule for each of them.

Another option you could try is for you to add dynamicBarrier objects based on some allocation tracking rather than using rules.

(I still don't see why this is a problem for caching since we have to evaluate each rule each time the path finding algorithm is called - and we can still cache by barrier/rule combination for the same call using a map. One hundred rules each with one barrier is the same as one rule with 100 barriers - both mean we need to store 100 values - it's just one is much easier for the user to implement. A simple checkbox for the rule to "evaluate per barrier" will give the best of both worlds)