mod.rs

// Creates a module
// Contains other modules which hold functions,
// structs, enums, constants, traits
// You use modules to organize your code and to make
// parts of it private (Everything is Private by Default)
// Parent modules can't access private items in child modules
// but children can always access parent items

mod pizza_order {

    // To access the struct and the part to make public must both use pub
    pub struct Pizza {
        pub dough: String,
        pub cheese: String,
        pub topping: String,
    }

    // Implement functionality for the Pizza struct
    impl Pizza {
        pub fn lunch(topping: &str) -> Pizza {
            Pizza {
                dough: String::from("regular dough"),
                cheese: String::from("mozzarella"),
                topping: String::from(topping),
            }
        }
    }

    // help_customer is public so functions can call it
    pub mod help_customer {
        // This function is private
        fn seat_at_table() {
            println!("Customer seated at table");
        }

        // Making help_customer public doesn't make this child
        // function public so we must also make it public
        pub fn take_order() {
            seat_at_table();

            // super allows me to access pizza in the parent scope
            let cust_pizza: super::Pizza =
                super::Pizza::lunch("veggies");

            serve_customer(cust_pizza);
        }

        fn serve_customer(cust_pizza: super::Pizza){
            println!("The customer is served a regular pizza with {}", cust_pizza.topping);
        }

    }
}

// This is the public function that allows our other file access
pub fn order_food() {
    crate::restaurant::pizza_order::help_customer::take_order();
}