rust - 如何在模块内部使用 const？

Question

我有以下代码:

mod delicious_snacks {
    use self::fruits::PEAR as fruit;
    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
    );
}

我收到一个错误，水果和蔬菜 are private当我尝试打印它们时:

error[E0603]: constant `fruit` is private
  --> src/main.rs:19:31
   |
19 |             delicious_snacks::fruit,
   |                               ^^^^^

error[E0603]: constant `veggie` is private
  --> src/main.rs:20:31
   |
20 |             delicious_snacks::veggie
   |                               ^^^^^^

谁能解释一下并帮助我解决这个问题？

Answer 1

用 use 定义的项目的可访问性独立于已使用项目的可访问性。这意味着 PEAR 是公开的，而 use self::fruits::PEAR as fruit; 是私有(private)的。您必须公开导出这些项目:

pub use self::fruits::PEAR as fruit;
pub use self::veggies::CUCUMBER as veggie;

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