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)

Using traits with generics – trait bounds

Now that we have a decent idea about generics and traits, we can explore ways in which we can combine them to express more about our interfaces at compile time. Consider the following code:

// trait_bound_intro.rs

struct Game;
struct Enemy;
struct Hero;

impl Game {
fn load<T>(&self, entity: T) {
entity.init();
}
}

fn main() {
let game = Game;
game.load(Enemy);
game.load(Hero);
}

In the preceding code, we have a generic function, load, on our Game type that can take any game entity and load it in our game world by calling init() on all kinds of T. However, this example fails to compile with the following error:

So, a generic function taking any type T cannot know or assume by default the init method exists on T. If it did, it wouldn't be generic at all, and would only be able to accept types that have...