Book Image

Rust Standard Library Cookbook

By : Jan Hohenheim, Daniel Durante
Book Image

Rust Standard Library Cookbook

By: Jan Hohenheim, Daniel Durante

Overview of this book

Mozilla’s Rust is gaining much attention with amazing features and a powerful library. This book will take you through varied recipes to teach you how to leverage the Standard library to implement efficient solutions. The book begins with a brief look at the basic modules of the Standard library and collections. From here, the recipes will cover packages that support file/directory handling and interaction through parsing. You will learn about packages related to advanced data structures, error handling, and networking. You will also learn to work with futures and experimental nightly features. The book also covers the most relevant external crates in Rust. By the end of the book, you will be proficient at using the Rust Standard library.
Table of Contents (12 chapters)

How it works...

Calling env::args() returns an iterator over the provided parameters[6]. By convention, the first command-line parameter on most operating systems is the path to the executable itself [12].

We can access specific parameters in two ways: keep them as an iterator [11] or collect them into a collection such as Vec[23]. Don't worry, we are going to talk about them in detail in Chapter 2, Working with Collections. For now, it's enough for you to know that:

  • Accessing an iterator forces you to check at compile time whether the element exists, for example, an if let binding [12]

  • Accessing a vector checks the validity at runtime

This means that we could have executed lines [26] and [29] without checking for their validity first in [25] and [28]. Try it yourself, add the &args[3]; line at the end of the program and run it.

We check the length anyways because it is considered good style to check whether the expected parameters were provided. With the iterator way of accessing parameters, you don't have to worry about forgetting to check, as it forces you to do it. On the other hand, by using a vector, you can check for the parameters once at the beginning of the program and not worry about them afterward.