Rust Namespacing with use Declaration

Introduction

In this lab, the use declaration is used to eliminate the need for manual scoping in Rust and make names available without explicitly specifying the namespace.

Note: If the lab does not specify a file name, you can use any file name you want. For example, you can use main.rs, compile and run it with rustc main.rs && ./main.

Skills Graph

use

The use declaration can be used so manual scoping isn't needed:

// An attribute to hide warnings for unused code.
#![allow(dead_code)]

enum Status {
    Rich,
    Poor,
}

enum Work {
    Civilian,
    Soldier,
}

fn main() {
    // Explicitly `use` each name so they are available without
    // manual scoping.
    use crate::Status::{Poor, Rich};
    // Automatically `use` each name inside `Work`.
    use crate::Work::*;

    // Equivalent to `Status::Poor`.
    let status = Poor;
    // Equivalent to `Work::Civilian`.
    let work = Civilian;

    match status {
        // Note the lack of scoping because of the explicit `use` above.
        Rich => println!("The rich have lots of money!"),
        Poor => println!("The poor have no money..."),
    }

    match work {
        // Note again the lack of scoping.
        Civilian => println!("Civilians work!"),
        Soldier  => println!("Soldiers fight!"),
    }
}

Summary

Congratulations! You have completed the Use lab. You can practice more labs in LabEx to improve your skills.