Book Image

Mastering Rust - Second Edition

By : Rahul Sharma, Vesa Kaihlavirta
Book Image

Mastering Rust - Second Edition

By: Rahul Sharma, Vesa Kaihlavirta

Overview of this book

Rust is an empowering language that provides a rare combination of safety, speed, and zero-cost abstractions. Mastering Rust – Second Edition is filled with clear and simple explanations of the language features along with real-world examples, showing you how you can build robust, scalable, and reliable programs. This second edition of the book improves upon the previous one and touches on all aspects that make Rust a great language. We have included the features from latest Rust 2018 edition such as the new module system, the smarter compiler, helpful error messages, and the stable procedural macros. You’ll learn how Rust can be used for systems programming, network programming, and even on the web. You’ll also learn techniques such as writing memory-safe code, building idiomatic Rust libraries, writing efficient asynchronous networking code, and advanced macros. The book contains a mix of theory and hands-on tasks so you acquire the skills as well as the knowledge, and it also provides exercises to hammer the concepts in. After reading this book, you will be able to implement Rust for your enterprise projects, write better tests and documentation, design for performance, and write idiomatic Rust code.
Table of Contents (19 chapters)

Casting and coercion

Casting is a mechanism of downgrading or upgrading a type to some other type. When the casting happens implicitly, it is called coercion. Rust also allows for casting types at various levels. The very obvious candidates are primitive numeric types. You may have the need to cast a u8 type to promote to u64 or to truncate i64 to i32. To perform trivial casts, we use the as keyword, like so:

let a = 34u8;
let b = a as u64;

It's not only primitive types—casting is supported at higher-level types too. We can also cast a reference of a type to its trait object, if it implements that particular trait. So we can do something like the following:


use std::fmt::Display;

fn show_me(item: &Display) {
println!("{}", item);

fn main() {
let a = "hello".to_string();
let b = &a;
// let c...