mod front_of_house {
    pub mod hosting {
        pub fn add_to_waitlist() {
            println!("add_to_waitlist")
        }

        fn seat_at_table() {}
    }

    mod serving {
        fn take_order() {}

        fn server_order() {}

        fn take_payment() {}
    }
}

絕對路徑（absolute path）從 crate 根開始齿桃，以 crate 名或者字面值 crate 開頭。
相對路徑（relative path）從當(dāng)前模塊開始煮盼，以 self短纵、super 或當(dāng)前模塊的標(biāo)識符開頭。

pub fn eat_at_restaurant() {
    crate::front_of_house::hosting::add_to_waitlist();
    front_of_house::hosting::add_to_waitlist();
}

使用 super 開頭來構(gòu)建從父模塊開始的相對路

fn serve_order() {}
mod back_of_house {
    fn fix_incorrect_order() {
        cook_order();
        super::serve_order();
    }

    fn cook_order() {}
}

創(chuàng)建公有的結(jié)構(gòu)體和枚舉

mod back_of_house1 {
     // 帶有公有和私有字段的結(jié)構(gòu)體 , 結(jié)構(gòu)體可以單個(gè)共有
    pub struct Breakfast {
        pub toast: String,
        seasonal_fruit: String,
    }
    impl Breakfast {
        pub fn summer(toast: &str) -> Breakfast {
            Breakfast {
                toast: String::from(toast),
                seasonal_fruit: String::from("peaches"),
            }
        }
    }
}

pub fn eat_at_restaurant1() {
    let mut meal = back_of_house1::Breakfast::summer("Tom");
    meal.toast = String::from("Wheat");
    println!("I'd like {} toast please", meal.toast);
}

如果將枚舉設(shè)為公有孕似，則它的所有成員都將變?yōu)楣?/p>

mod back_of_house2 {
    pub enum Appetizer {
        Soup,
        Salad,
    }
}

pub fn eat_at_restaurant3() {
    let o1 = back_of_house2::Appetizer::Salad;
    let o2 = back_of_house2::Appetizer::Soup;
}

使用 use 關(guān)鍵字將名稱引入作用域(簡化路徑使用)

mod front_of_house4 {
    pub mod hosting {
        pub fn add_to_waitlist() {}
    }
}

use crate::front_of_house4::hosting;

pub fn eat_at_restaurant4() {
    hosting::add_to_waitlist()
}

use std::collections::HashMap;
 fn main() {
     let mut map = HashMap::new();
     map.insert(1, 2);
     println!("map = {:?}", map);
 }

最好只引入到父模塊踩娘，防止沖突

use std::fmt;
use std::io;
 fn function1() -> fmt::Result {
      --snip--
 }
 fn function2() -> io::Result<()> {
      --snip--
 }

使用 as 關(guān)鍵字提供新的名稱

use std::fmt::Result;
use std::io::Result as IoResult;

 fn fn1() -> Result {}
 fn fn2() -> IoResult<()> {}

當(dāng)使用 use 關(guān)鍵字將名稱導(dǎo)入作用域時(shí)，在新作用域中可用的名稱是私有的喉祭。如果為了讓調(diào)用你編寫的代碼的代碼能夠像在自己的作用域內(nèi)引用這些類型养渴，可以結(jié)合 pub 和 use。這個(gè)技術(shù)被稱為 “重導(dǎo)出（re-exporting）”泛烙，因?yàn)檫@樣做將項(xiàng)引入作用域并同時(shí)使其可供其他代碼引入自己的作用域理卑。

mod front_of_house5 {
    pub mod hosting5 {
        pub fn add_to_waitlist() {}
    }
}

pub use crate::front_of_house5::hosting5;

pub fn eat_at_restaurant5() {
    hosting::add_to_waitlist();
    hosting::add_to_waitlist();
    hosting::add_to_waitlist();
}

使用外部包

 [dependencies]
 rand = "0.5.5"
use rand::Rng;

fn main() {
    let secret_number = rand::thread_rng().gen_range(1, 101);
}

嵌套路徑來消除大量的 use 行

 use std::cmp::Ordering;
 use std::io;
 use std::{cmp::Ordering, io};

通過 glob 運(yùn)算符將所有的公有定義引入作用域

use std::collections::*;