trait_dispatch.rs

trait Foo {
    fn method(&self) -> String;
}

impl Foo for u8 {
    fn method(&self) -> String {
        format!("u8: {}", *self)
    }
}

impl Foo for String {
    fn method(&self) -> String {
        format!("string: {}", *self)
    }
}

// 静的ディスパッチ
fn do_static_dispatch<T: Foo>(x: &T) {
    println!("{}", x.method());
}

// 動的ディスパッチ
fn do_dynamic_dispatch(x: &Foo) {
    println!("{}", x.method());
}

fn main() {
    let x = 5u8;
    let y = "Hello".to_string();
    do_static_dispatch(&x);
    do_static_dispatch(&y);

    do_dynamic_dispatch(&x);
    do_dynamic_dispatch(&y);
}