I’d consider “mark it clearly in the docs” a reasonable outcome. I spent quite some time chasing this and trying to reproduce the problem.

Another possible fix would be “only ever return string keys” but I understand that this would break some existing mods.

So it seems there is an explanation to the behavior but I still think it is kind of a bug. The station in question looks like this:

Screenshot 2025-09-14 at 16.43.36.png

There are two rails. One straight rail that the station is connected to and a curved rail that connects (on the left side) to ...

So I have a train. The train is departing a station (wait_station -> on_the_track) and has a path (and a path_end_rail, but not a path_end_station):

Screenshot 2025-09-14 at 08.52.06.png

If I ask the train manager to calculate the path for the train itself, it works fine:

game.train_manager ...

<sad>, but not super-surprised. I assumed it would be something like this. Thank you for the thorough explanation, this helps me a lot to understand how the game sends events.

Let me see if I can figure out a workaround for my use-case.

(I don't think there is a way for a mod to register a ...

I have two mods. Let's call them "Logistic Train Network" and "Train Tracker". Both listen to `on_train_changed_state`.

When a train stops at a station (transition from `arrive_station` to `wait_station`), the first mod (Logistic Train Network) receives an event with `old_state` = 5 (arrive_station ...

Cool, thanks! This is a part of the lua api that I have not yet ventured into. I think this is what I was looking for.

I had a user asking whether it is possible to expose that information to the circuit network (https://github.com/hgschmie/factorio-inventory-sensor-improved/issues/4) and I started poking around to see whether this information is available.

I guess having a way to ask a requester or buffer chest ...

for a mod, I intercept the "on_pre_build" event so that I can correct information if a blueprint is placed that contains some of my entities. That event contains the direction in which all following entities are built (direction) and also flags whether the blueprint has been flipped horizontally or ...

I was looking for a simple way to find out for a requester or buffer chest how many items are currently "in flight" to be delivered.

Basically programmatic access to this information:
Is that possible?

Thanks for the explanation. Also demonstrates that the forum search function is useless (nothing turns up at search.php?keywords=respect_insert_limits)

FactorioBot wrote: Fri Aug 22, 2025 11:43 am
Modding

• Added LoaderPrototype::respect_insert_limits.

This sounds interesting. What does it do? There is no information in the API docs besides "that exists now".

Yes. Sorry for not being clearer in the original post, it was late at night.

The “numeric key becomes a string key” is the problem/bug.

You can not reproduce this by using the lua command line or the debugger console; it is specific to LuaGuiElement.add and tags.

Ok, lets slow down and reiterate. When i run following command:

/c
local foo = { [3] = "onSort inside foo" }
game.print(serpent.line(foo))
game.print(foo[3])

local bar = { [1] = "onSort inside bar" }
game.print(serpent.line(bar))
game.print(bar[1])

local qux = { "onSort inside qux ...

While I agree with the "it is all user space interpretation", the surprising part (and the bug IMHO) is that one should be able to expect to read back from the table what you wrote. So when I create a new LuaGuiElement with tags:



child = parent.add {
...
tags = {
xxx = {
[defines.events.on ...

consider this code:

local handler = {
[defines.events.on_gui_checked_state_changed] = 'onSort',
}

local child = element.add {
type = 'checkbox',
...
tags = {
value = sort_value,
entity_type = entity_type,
handler = handler,
},
}


Looking at this in the debugger shows this:

Screenshot ...

Thanks. I expected as much. I won't bother reimplementing.

I have a mod with a GUI window whose main component is a tabbed-pane. In each tab, there is a vertical frame that contains a scroll pane, which in turn contains a table.

Each of these scroll panes may have a different width. However, the window only resizes on the scroll pane in the first tab. Any ...

Thanks for looking into this. I agree, it is a minor issue.

- Open the map view, find a train on the map. Zoom in on the train, click on the locomotive

=> The fuel tab is selectable

Screenshot 2025-08-14 at 12.00.19.png

- Open the locomotive GU directly (e.g. through the train view)

=> The fuel tab is grayed out

Screenshot 2025-08-14 at 12.01.14.png ...