Jan Kwakkel

The change looks fine to me. I suggest we get these various maintenance PRs merged asap.

Why would this have to wait for 3.0? I am not sure I understand how this is a breaking change?

In case of the Boltzman model, if you retrieve wealth not from the agent set, but directly from SystemState, the model with SystemState is about 10% faster (despite the many...

The aim of SystemState is to have a convenient way of describing the subset of state variables that one is interested in at any given time instant. This can be...

> For simplicity let's assume for the Boltzmann model the system state is captured by wealth and the gini index. We can already capture those with the normal data collector....

The bigger picture is indeed being able to listen to events. It would be trivial to use AgentState and ModelState for firing StateChangeEvents and add a way to subscribe to...

I have been thinking about this quite a bit. In my view, there are 3 different questions that have to be answered. 1. **Should MESA have some form of event...

So, I played around a bit more. Adding event sourcing can be quite simple: ```python from enum import StrEnum, auto class Event(StrEnum): STATE_CHANGE = auto() AGENT_ADDED = auto() AGENT_REMOVED =...

> IIUC, marking the attributes with SystemState, AgentState, ModelState turns them to be effectively immutable (and thus can be pickled), and in effect, they become inspectable at any given time....

> But I wonder if we could indeed combine data collector with this push based approach. Playing around a bit it seems to be possible to add AgentState descriptors on...