Rust YouTube Bits

Introduction

As I strive to improve I wanted a page for just stuff I watch on YouTube

Deref

Rust list c++ has a deference operator. You can deference with a *. But with wonderful rust you can make one. In the video from The Dev Method, they made an implementation of a box (smart pointer) and demonstrated how to do this

struct MyBox<T>(T);

impl<T> MyBox<T> {
    fn new(x: T) -> MyBox<T> {
        MyBox(x)
    }
}

fn main() {
    println!("Hello, world!");
    let x = 5;
    let y = MyBox::new(x);
    assert_eq!(5, x);
    assert_eq!(5, *y); // Error no deref
}

To solve this we implement the deref trait

use std::ops::Deref;

impl<T> Deref for MyBox<T> {
    type Target = T;
    fn deref(&self) -> &T {
        &self.0
    }
}

Patterns

From Let's get rust they were very keen to stress you should implement

• Debug
• Clone
• Default
• PartialEq

They also mentioned

• Send
• Sync

For the Send and Sync they suggested adding a test to make sure send, sync are implemented

fn is_normal<T: Sized + Send + Sync + Unpin>() {}
#[test]
fn is_normal_types() {
   is_normal::<User>();
}

They also mentioned implementing these where applicable and possible making in a feature to remove dependency on serde.

• Serialize
• Deserialize

Handling Option and Result and Error

This was quite a nice revisit known tricks from Code to the Moon. I never knew of these

• ok_or
• unwrap_or

General learnings are

• unwrap unwraps an Option or Result
• .ok converts between Result and Option
• .map converts to the same container but with a different type e.g.

struct MyApiError;

fn test() -> Result<i32, ParseIntError> {
    let x: i32 = "5".parse()?;
    Ok(x)
}

fn call_test() -> Result<i32, MyApiError> {
    test().map_err(|_| MyApiError)
}