Events and filters

Mark handlers with #[factorio_rs::event]. The CLI wires them into control.lua via script.on_event.

Handler rules

• The function name must match the Factorio event name (on_built_entity, on_singleplayer_init, …).
• The event type comes from the attribute or from a parameter whose type ends in Event (e.g. OnBuiltEntityEvent -> OnBuiltEntity).

use factorio_rs::prelude::*;
use factorio_rs::factorio_api::events::{OnBuiltEntityEvent, OnBuiltEntityFilter};

#[factorio_rs::event(OnSingleplayerInit)]
pub fn on_singleplayer_init() {
    println!("Hello");
}

#[factorio_rs::event]
pub fn on_built_entity(event: OnBuiltEntityEvent) {
    let _ = event.entity;
}

#[factorio_rs::event(filter = [OnBuiltEntityFilter::name("inserter")])]
pub fn on_built_entity(event: OnBuiltEntityEvent) {
    println!("inserter built");
}

A single filter expression (not only arrays) is also accepted:

#[factorio_rs::event(filter = OnBuiltEntityFilter::type_("inserter"))]
pub fn on_built_entity(event: OnBuiltEntityEvent) {}

Filters are type-checked at compile time. Events that do not support filters reject a filter = argument.

Generated Lua

script.on_event(defines.events.on_built_entity, function(event)
  control.on_built_entity(event)
end, { { filter = "name", name = "inserter" } })

(control may be renamed when [emit].lua_module_prefix is set.)

Filter limitations

• Filter method arguments must be string literals (e.g. "inserter"), not variables or expressions.
• Only events that declare a filter type accept filter = ....
• Handlers must live in a control-stage module.

See also Language support for if let / Option patterns commonly used inside handlers.