Modules in Rust

A module tree inside one file: mod declares, pub opens, paths reach in.

mod tours {
    pub mod rust {
        pub fn count() -> usize {
            11
        }
    }

    pub fn label() -> String {
        format!("{} tours", rust::count())
    }
}

fn main() {
    println!("{}", tours::label());
    println!("{}", tours::rust::count());
    println!("{}", crate::tours::rust::count());
}

How it works

1. Items are private to their module until marked pub.
2. A nested module needs pub at every level of the path.
3. crate:: starts a path from the root.

Keywords and builtins used here

• String
• count
• crate
• fn
• label
• main
• mod
• pub
• usize

The run, in numbers

Lines

17

Characters to type

256

Tokens

91

Three-star pace

100 tpm

At the three-star pace of 100 tokens a minute, this run takes about 55 seconds.

Type this snippet

Step 1 of 3 in Modules & visibility, step 1 of 12 in Modules, tests & macros.

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