题外话

篇目

泛型类型实例

#![allow(unused_variables)]
struct Struct<T> (T);

// clear && cargo run --example generics_type_hello
fn main() {
    let instance = Struct(0u8);
    let instance = Struct(0u32);
    let instance = Struct('0');
    let instance = Struct(0.0);
    let instance = Struct("0.0");
    let instance = Struct(());
    let instance = Struct([0]);
    let instance = Struct(Struct(0.0f64));
}

泛型方法实例

#![allow(unused_variables)]
use std::fmt::Debug;

fn print<T: Debug>(x: T) {
    println!("{:?}", x);
}

// clear && cargo run --example generics_fn_hello
fn main() {
    print(0u8);
    print(0u32);
    print('0');
    print(0.0);
    print("0.0");
    print(());
    print([0]);
}

泛型实现实例

#![allow(unused_variables)]
struct Struct<T> (T);

impl<S> Struct<S> {
    fn get(&self) -> &S {
        &self.0
    }
}
// clear && cargo run --example generics_impl_hello
fn main() {
    let instance = Struct(0u8);
    instance.get();
    let instance = Struct(0u32);
    instance.get();

    let instance = Struct('0');
    instance.get();
    let instance = Struct("0");
    instance.get();
}

泛型特质实例

#![allow(unused_variables)]
struct Struct<T> (T);

trait Trait<U> {
    fn get(&self) -> &U;
}

impl<S> Trait<S> for Struct<S> {
    fn get(&self) -> &S {
        &self.0
    }
}

// clear && cargo run --example generics_trait_hello
fn main() {
    let instance = Struct(0u8);
    instance.get();
    let instance = Struct(0u32);
    instance.get();

    let instance = Struct('0');
    instance.get();
    let instance = Struct("0");
    instance.get();
}

// Dynamically Sized Types (DSTs)
// https://doc.rust-lang.org/nomicon/exotic-sizes.html
struct MySuperSliceable<T: ?Sized> {
    info: u32,
    data: T
}

fn main() {
    let sized: MySuperSliceable<[u8; 8]> = MySuperSliceable {
        info: 17,
        data: [0; 8],
    };

    let dynamic: &MySuperSliceable<[u8]> = &sized;

    // prints: "17 [0, 0, 0, 0, 0, 0, 0, 0]"
    println!("{} {:?}", dynamic.info, &dynamic.data);
}

参考资料