Maybe I’m misunderstanding what the system is, is click_handler in the post a system, and if so, do systems only declare a single component of an entity as their input?
The way I figured would make sense was that, in the engine/game itself, the BoundaryComponent would have an additional field for registered scripts or that there would be an additional component just for registered scripts, to keep components lean. Not sure if that actually worked out in reality.
Then there would be a system for clicking on boundaries that would call such a script, if available. It’s probably a poor example, but since that system doesn’t touch much else, only the boundary component gets passed into the script. That’s not supposed to be a rule, though. I probably should clarify that on the post later on…