Hi!
I'm currently working on a composite entity mod and ran into a classic problem: displaying dynamic data from a hidden internal entity inside the main host's tooltip.
Since Factorio 2.1.7 we have set_tooltip_field, but using it for fast-changing data means running heavy Lua scripts, managing tables in storage, and hammering the C-boundary via on_nth_tick. On megabases, this is a total UPS killer.
I’ve created a Modding Interface Request on the official forums proposing a native C++ solution: allowing us to register a flat array of "donor" entities to a host entity just once upon creation (on_built_entity). The engine would then lazily handle the tooltip rendering on the C++ side only when the tooltip is actively being rendered, with 0% runtime Lua overhead.
I think this feature could be incredibly useful for Compact Circuits as well — for example, natively forwarding logic signals from internal hidden combinators straight to the main tooltip without any background Lua ticking.
If you find this idea helpful for your mod, please consider dropping a comment or a +1 in the forum thread to show Wube that there is a real demand for this from the composite-modding community.
Here is the link to the request: https://forums.factorio.com/134073
Thanks for your amazing work on Compact Circuits!