traits_demo

Path: examples/traits_demo.

Shows how powerful same-crate traits are in factorio-rs: Alert lives in shared.alert, control uses it, a default announce, a type-specific override, static method calls, and one helper that takes &dyn Alert (Lua fat pointer + vtable).

shared/alert.rs

pub trait Alert {
    fn title(&self) -> &'static str;
    fn priority(&self) -> i64;

    fn announce(&self) {
        println!("[alert p{}] {}", self.priority(), self.title());
    }
}

// control
use crate::shared::alert::Alert;

struct PowerDrop {
    machine: &'static str,
    percent: i64,
}

impl Alert for PowerDrop {
    fn title(&self) -> &'static str {
        self.machine
    }

    fn priority(&self) -> i64 {
        100 - self.percent
    }
}

// BeltJam overrides announce; ScienceStall uses the default.

fn shout(alert: &dyn Alert) {
    alert.announce();
}

fn priority_of(alert: &dyn Alert) -> i64 {
    alert.priority()
}

let total = priority_of(&power)
    + priority_of(&belt)
    + priority_of(&science);

On OnSingleplayerInit the example:

1. Calls .announce() on concrete values (static dispatch).
2. Sums priorities through priority_of(&...) (dyn).
3. Routes three different alert kinds through the same shout helper.

#[test]s cover static priorities and the dyn sum (no Factorio binary required for those).

Try it

cd examples/traits_demo
factorio-rs build
factorio-rs install --open   # optional - watch [alert ...] lines on init
factorio-rs test             # unit tests; Factorio only needed for ignored games

Limits (today)

Associated types are supported without bounds/defaults; dyn coerce rejects traits that declare them. No generics or supertraits - see Supported Rust.