Load and Save functionality

[atyshka]

Currently, Behaviours cannot be serialized with pickle, and there seems to be no other easy way to load and save trees. Could I open a PR for making this library pickle-friendly? Is there a reason it isn't already?

[stonier]

Just that pickle can be fickle and even if the behaviours in this library were pickle-friendly, it might be notoriously painful for a user to construct their behaviours to be pickle-friendly given that tree behaviours usually connect to to other entities on sockets or in databases (pickle - unpicklable objects).

Just to be clear, are you after a serialised format that can be used for constructing a tree in it's initial state, or one that can re-launch a tree mid-run?

The former is probably a realisable goal, the latter much harder.

[stonier]

See also #63

[atyshka]

I'm after the former scenario: I want to allow users to design a behavior tree without code, then save the resulting model (without any state) to be executed later. Agreed that pickle can be a pain though

[stonier]

Got it.

Only reason a behaviour tree description format (and editor) doesn't exist yet is that the use cases at my two companies didn't require it. For the former, scripting was preferred and for the latter, the trees were merely an execution layer designed to realise a domain specific (no relation to behavior trees) language.

I can imagine having a yaml or json format, backed by a schema and followed shortly thereafter by an editor would be very useful for some use cases. The requirements at work just haven't lined up and not that much time outside of work. Would be happy to accomodate someone else's efforts though.