[boskid] How to get the ID of a custom-event?

[Pi-C]

We can now define custom events as CustomEventPrototype during the data stage. We can also use the name (string) of that prototype with script.raise_event and script.on_event. However, it seems that the name passed on with the event data is numeric:

12490.617 Script @__Pi-C_lib__/libs/debugging.lua:185: Yes: raising event minime_exchanged_characters!
12490.617 Script @__Pi-C_lib__/libs/debugging.lua:185:
====================================================================================================
Entered event script for unnamed event
Event data: player_index = 1, old_character = character "character" (517), new_character = character "IRobot_character_skin" (518), old_unit_number = 517, new_unit_number = 518, tick = 297822, mod_name = "minime"
(@__minime__/scripts/events.lua: 297)
====================================================================================================

12490.617 Script @__Pi-C_lib__/libs/debugging.lua:185:
----------------------------------------------------------------------------------------------------
Entered function event_handler({mod_name = "minime", name = 218, new_character = "[LuaEntity: IRobot_character_skin at [gps=6.8,-2.9]]", new_unit_number = 518, old_character = "[LuaEntity: character at [gps=7.0,-2.7]]", old_unit_number = 517, player_index = 1, tick = 297822})
(@__minime__/scripts/events.lua: 256)
----------------------------------------------------------------------------------------------------

Is there any way to derive the prototype name (string) from event.name(numeric)?

[wizmut]

Can you post the relevant code?

I assume you're looking at these pages:

https://lua-api.factorio.com/latest/eve ... InputEvent - particularly "selected_prototype"
https://lua-api.factorio.com/latest/pro ... otype.html - which mentions "include_selected_prototype" should be set to true
https://lua-api.factorio.com/latest/con ... eData.html - "derived_type"

[Pi-C]

Can you post the relevant code?

Sure. I create the event prototype in data.lua:

Code: Select all

data:extend({
  {
    type = "custom-event",
    name = "minime_exchanged_characters",
  }
})

In control, I raise the event like this:

Code: Select all

  local pass_on = {
    player_index = player.index,
    old_character = old_char,
    new_character = new_char,
    old_unit_number = old_id,
    new_unit_number = new_id,
    god_mode = data.god_mode,
    editor_mode = data.editor_mode
  }
  script.raise_event("minime_exchanged_characters", pass_on)

And I can listen to the event like that:

Code: Select all

script.on_event("minime_exchanged_characters", function(event) … end)

This is new since Factorio 2.0. Before, you had to use script.generate_event_name to generate a numeric ID that you'd use when raising the event. However, the numeric ID could change, depending what other new/removed mods would generate their own events. So if you wanted to listen to a custom event, you first had to use remote calls to ask the other mod for the event ID.

[Pi-C]

@boskid: Hi! As I've just noticed you've taken an interest in this, there is a related issue with LuaBootstrap::get_event_handler. Currently, passing on the name of a custom event will result in an error:

Code: Select all

11413.654 Error MainLoop.cpp:1432: Exception at tick 286131: Error while running command "minime-show-active-events": Unknown custom-input name: minime_exchanged_characters
stack traceback:
	[C]: in function 'get_event_handler'

While we could work around this if we'd get the numeric ID of custom events, it may also be a good idea to allow the string name of a custom event as argument for script.get_event_handler. I hope that I don't come across as too greedy!

Also, could you tell me why LuaBootstrap.generate_event_name is still available? It's a bit confusing to have two techniques to achieve the same thing (define a custom event). My guess is, it's still there for backwards compatibility but may be removed in the future – can you confirm that, or is there another reason?

[Xorimuth]

Also, could you tell me why LuaBootstrap.generate_event_name is still available? It's a bit confusing to have two techniques to achieve the same thing (define a custom event). My guess is, it's still there for backwards compatibility but may be removed in the future – can you confirm that, or is there another reason?

I can see some extremely niche uses for wanting to be able to dynamically generate events perhaps? Probably not something that would be worth adding if we'd already had the prototype-based custom events but since it is there already I guess it may as well stay.

[Klonan]

Also, could you tell me why LuaBootstrap.generate_event_name is still available? It's a bit confusing to have two techniques to achieve the same thing (define a custom event). My guess is, it's still there for backwards compatibility but may be removed in the future – can you confirm that, or is there another reason?

It is still useful for custom scenarios

[Pi-C]

I can see some extremely niche uses for wanting to be able to dynamically generate events perhaps?

It is still useful for custom scenarios

Yes, makes sense. But that means we'd still have to keep two methods for registering custom events: the easy way by checking prototypes.custom_events, and by asking the other mods for the event ID per remote call. This could be circumvented if we could pass on a string (the name of the custom-event) and there was a map from event names to numeric IDs (similar to defines.events, but dynamic). Needless to say, I'm not sure whether this even could be implemented …