Working with Rust

Modules

Use Rust modules to break your code up into separate files that live in the same project source directory. Libraries are used for files outside the source directory.

Module Example

The example uses the following directory structure:

project/
|--- Cargo.toml
|--- src/
     |--- main.rs
     |--- october.rs

Note: The file october.rs is the module code to be used within main.rs.

pub fn greet(s: &str) -> {
    println!("Happy Halloween {}", s);
}

mod october;
 
fn main() {
    october::greet("Marcus");
}

Note the additional pub definition on the function within the module. By default, all functions are private in a module and must be declared public to be used externally.

Directory Module

When using modules Rust will initially look by file looking for module-name.rs but will also look for a mod.rs file in a directory with the module name.

In the above example, you could move the october.rs file to mod.rs and placed inside a october directory. The main.rs file would stay the same.

project/
|--- Cargo.toml
|--- src/
     |--- main.rs
     |--- october/
          |--- mod.rs