register_fn_constraints2.rs

use std::any::Any;

#[derive(Debug)]
struct Engine {
    x: i32
}

trait FnRegister1V {
    fn register<T: Fn(U)->V, U, V>(&mut self, name: &str, f: T);
}

impl FnRegister1V for Engine {
    fn register<T: Fn(U)->V, U, V>(&mut self, name: &str, f: T) {
        self.x += 2;
    }
}

trait FnRegister2V {
    fn register<T: Fn(U, V)->W, U, V, W>(&mut self, name: &str, f: T);
}

impl FnRegister2V for Engine {
    fn register<T: Fn(U, V)->W, U, V, W>(&mut self, name: &str, f: T) {
        self.x += 2;
    }
}

fn id(x: i32) -> i32 {
    x
}

fn main() {
    let mut engine = Engine { x: 0 };

    engine.register("foo", id);

    println!("Engine: {:?}", engine);
}