如何从兄弟模块导入？

Question

在src/lib.rs我有以下

extern crate opal_core;

mod functions;
mod context;
mod shader;

然后在src/context.rs我有类似的东西，它试图从src/shader.rs导入符号：

use opal_core::shader::Stage;
use opal_core::shader::Shader as ShaderTrait;
use opal_core::GraphicsContext as GraphicsContextTrait;

use functions::*; // this import works fine
use shader::*; // this one doesn't

pub struct GraphicsContext {
    functions: Gl
}

fn shader_stage_to_int(stage: &Stage) -> u32 {
    match stage {
        &Stage::Vertex => VERTEX_SHADER,
        &Stage::Geometry => GEOMETRY_SHADER,
        &Stage::Fragment => FRAGMENT_SHADER,
    }
}

impl GraphicsContextTrait for GraphicsContext {

    /// Creates a shader object
    fn create_shader(&self, stage: Stage, source: &str) -> Box<ShaderTrait> {
        let id;

        unsafe {
            id = self.functions.CreateShader(shader_stage_to_int(&stage));
        }

        let shader = Shader {
            id: id,
            stage: stage,
            context: self
        };

        Box::new(shader)
    }
}

问题是语句use shader::*;给出错误 unresolved import 。

我正在阅读文档，他们说use语句总是来自当前包的根（opal_driver_gl）所以我认为shader::*应该导入opal_driver_gl::shader::*但它似乎没有这样做。我是否需要在此处使用self或super个关键字？

谢谢你能提供帮助。

Answer 1

请注意，use的行为已从Rust 2015更改为Rust 2018.有关详细信息，请参阅What are the valid path roots in the use keyword?。

Rust 2018

要在同一级别导入模块，请执行以下操作：

<强> random_file_0.rs

// Note how this is a public function. It has to be in order to be
// usable from other files (in this case `random_file_1.rs`)
pub fn do_something() -> bool {
    true
}

<强> random_file_1.rs

use super::random_file_0;

#[test]
fn do_something_else() {
    assert!(random_file_0::do_something());
}

或替代 random_file_1.rs ：

use crate::random_file_0;

#[test]
fn do_something_else() {
    assert!(random_file_0::do_something());
}

<强> lib.rs

mod random_file_0;
mod random_file_1;

有关更多信息和示例，请参阅Rust By Example。如果这不起作用，则显示以下代码：

fn function() {
    println!("called `function()`");
}

mod cool {
    pub fn function() {
        println!("called `cool::function()`");
    }
}

mod my {
    fn function() {
        println!("called `my::function()`");
    }

    mod cool {
        pub fn function() {
            println!("called `my::cool::function()`");
        }
    }

    pub fn indirect_call() {
        // Let's access all the functions named `function` from this scope!
        print!("called `my::indirect_call()`, that\n> ");

        // The `self` keyword refers to the current module scope - in this case `my`.
        // Calling `self::function()` and calling `function()` directly both give
        // the same result, because they refer to the same function.
        self::function();
        function();

        // We can also use `self` to access another module inside `my`:
        self::cool::function();

        // The `super` keyword refers to the parent scope (outside the `my` module).
        super::function();

        // This will bind to the `cool::function` in the *crate* scope.
        // In this case the crate scope is the outermost scope.
        {
            use cool::function as root_function;
            root_function();
        }
    }
}

fn main() {
    my::indirect_call();
}

Rust 2015

要在同一级别导入模块，请执行以下操作：

random_file_0.rs：

// Note how this is a public function. It has to be in order to be
// usable from other files (in this case `random_file_1.rs`)
pub fn do_something() -> bool {
    true
}

random_file_1.rs：

use super::random_file_0;

#[test]
fn do_something_else() {
    assert!(random_file_0::do_something());
}

或替代random_file_1.rs：

use ::random_file_0;

#[test]
fn do_something_else() {
    assert!(random_file_0::do_something());
}

lib.rs：

mod random_file_0;
mod random_file_1;

以下是Rust By Example的先前版本中的另一个示例：

fn function() {
    println!("called `function()`");
}

mod my {
    pub fn indirect_call() {
        // Let's access all the functions named `function` from this scope
        print!("called `my::indirect_call()`, that\n> ");

        // `my::function` can be called directly
        function();

        {
            // This will bind to the `cool::function` in the *crate* scope
            // In this case the crate scope is the outermost scope
            use cool::function as root_cool_function;

            print!("> ");
            root_cool_function();
        }

        {
            // `self` refers to the current module scope, in this case: `my`
            use self::cool::function as my_cool_function;

            print!("> ");
            my_cool_function();
        }

        {
            // `super` refers to the parent scope, i.e. outside of the `my`
            // module
            use super::function as root_function;

            print!("> ");
            root_function();
        }
    }

    fn function() {
        println!("called `my::function()`");
    }

    mod cool {
        pub fn function() {
            println!("called `my::cool::function()`");
        }
    }
}

mod cool {
    pub fn function() {
        println!("called `cool::function()`");
    }
}

fn main() {
    my::indirect_call();
}