Module Sub Folders

This way of organizing works for major projects.

The code in mod.rs is the content of that module. All other files in the folder may in turn be exposed as submodules.

cargo new moddemo3

create the following directory structure

// main.rs

mod departments;

fn main() {
    println!("{:?}", get_standard_greetings());
    departments::sales::meet_customer(1);
    departments::service::meet_customer(3);
}

fn get_standard_greetings() -> String {
    return "Welcome to our store.".to_string();
}

// departments > mod.rs

fn get_number(num: i32) -> String {
    match num {
        1 => return "123-456-7890".to_string(),
        2 => return "987-654-3210".to_string(),
        _ => return "000-000-0000".to_string(),
    }
}

pub mod sales;
pub mod service;
pub mod tests;

// departments > sales.rs

pub fn meet_customer(num: i32) {
    println!("Sales : meet customer {num}");
    let phone_number = super::get_number(num);
    println!("Sales calling {}", phone_number);
}

// departments > service.rs

pub fn meet_customer(num: i32) {
    println!("Service : meet customer {num}");
    let phone_number = super::get_number(num);
    let ticket_number = self::get_service_ticket_number(num);
    println!("Calling {phone_number} with ticket number {ticket_number}");
}

fn get_service_ticket_number(num: i32) -> i32 {
    match num {
        1 => return 2452423,
        2 => return 2341332,
        _ => return 6868765,
    }
}

// departments > tests.rs

#[cfg(test)] // Only compiles when running tests
use crate::get_standard_greetings;

#[test]
fn test_customerphone() {
    assert_eq!("000-000-0000", super::get_number(4));
}

#[test]
fn test_standard_greeting() {
    assert_eq!("Welcome to our store.", get_standard_greetings());
}

Read more

{% embed url="https://spin.atomicobject.com/2022/01/24/rust-module-system/" %}