Rust-Modules

modules1.rs

The function make_sausage is declared as public, so it can be called outside the module sausage. But get_secret_recipe is not declared as public, so we can not access it outside the module.

mod sausage_factory {
    // Don't let anybody outside of this module see this!
    fn get_secret_recipe() -> String {
        String::from("Ginger")
    }

    pub fn make_sausage() {
        get_secret_recipe();
        println!("sausage!");
    }
}

fn main() {
    sausage_factory::make_sausage();
}

modules2.rs

In Rust, the pub keyword is used to declare the access permission of a function, variable or module as public, which means they can be accessed and use from outside other modules.

mod delicious_snacks {
    // TODO: Fix these use statements
    pub use self::fruits::PEAR as fruit;
    pub use self::veggies::CUCUMBER as veggie;

    mod fruits {
        pub const PEAR: &'static str = "Pear";
        pub const APPLE: &'static str = "Apple";
    }

    mod veggies {
        pub const CUCUMBER: &'static str = "Cucumber";
        pub const CARROT: &'static str = "Carrot";
    }
}

fn main() {
    println!(
        "favorite snacks: {} and {}",
        delicious_snacks::fruit,
        delicious_snacks::veggie
    );
}

modules3.rs

use std::time::{SystemTime, UNIX_EPOCH};

fn main() {
    match SystemTime::now().duration_since(UNIX_EPOCH) {
        Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
        Err(_) => panic!("SystemTime before UNIX EPOCH!"),
    }
}