Question

你好，我是悦创。

学员答疑：

• https://code.bornforthis.cn/?id=4e72084d-1eaf-44ed-8067-744671491574
• https://code.bornforthis.cn/?id=664ff169-41d6-409f-a05b-02ed42279759

问题代码：

// You can bring module paths into scopes and provide new names for them with // the `use` and `as` keywords.  #[allow(dead_code)] mod delicious_snacks {     // TODO: Add the following two `use` statements after fixing them.     use self::fruits::PEAR as fruits;     use self::veggies::CUCUMBER as veggies;      pub mod fruits {         pub const PEAR: &str = "Pear";         pub const APPLE: &str = "Apple";     }      pub mod veggies {         pub const CUCUMBER: &str = "Cucumber";         pub const CARROT: &str = "Carrot";     } }  fn main() {     println!(         "favorite snacks: {} and {}",          delicious_snacks::fruit,         delicious_snacks::veggie,     ); } 

报错：

D:\LagerA\rust\a-ex\rustlings git:[master] rustlings run modules2 error[E0425]: cannot find value `fruit` in module `delicious_snacks`   --> exercises/10_modules/modules2.rs:25:27    | 11 |         pub const PEAR: &str = "Pear";    |         ------------------------------ similarly named constant `fruits` defined here ... 25 |         delicious_snacks::fruit,    |                           ^^^^^ help: a constant with a similar name exists: `fruits`  error[E0425]: cannot find value `veggie` in module `delicious_snacks`   --> exercises/10_modules/modules2.rs:26:27    | 16 |         pub const CUCUMBER: &str = "Cucumber";    |         -------------------------------------- similarly named constant `veggies` defined here ... 26 |         delicious_snacks::veggie,    |                           ^^^^^^ help: a constant with a similar name exists: `veggies`  warning: unused import: `self::fruits::PEAR as fruits`  --> exercises/10_modules/modules2.rs:7:9   | 7 |     use self::fruits::PEAR as fruits;   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^   |   = note: `#[warn(unused_imports)]` on by default  warning: unused import: `self::veggies::CUCUMBER as veggies`  --> exercises/10_modules/modules2.rs:8:9   | 8 |     use self::veggies::CUCUMBER as veggies;    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^    For more information about this error, try `rustc --explain E0425`. error: could not compile `exercises` (bin "modul es2") due to 2 previous errors; 2 warnings emitted  Error: Ran exercises/10_modules/modules2.rs with errors 

Solution

#[allow(dead_code)] mod delicious_snacks {     // 使用 `use` 语句将常量导入到模块的顶层作用域     pub use self::fruits::PEAR as fruit;     pub use self::veggies::CUCUMBER as veggie;      pub mod fruits {         pub const PEAR: &str = "Pear";         pub const APPLE: &str = "Apple";     }      pub mod veggies {         pub const CUCUMBER: &str = "Cucumber";         pub const CARROT: &str = "Carrot";     } }  fn main() {     println!(         "favorite snacks: {} and {}",         delicious_snacks::fruit,         delicious_snacks::veggie,     ); }