标签：bsp earlier lob str like div app reason its
$ rustc --version
rustc 1.44.0 (49cae5576 2020-06-01)
将代码存在到不同的文件
main.rs
mod aa; fn main() { println!("------------------------------------"); aa::aa1(); }
mod aa表示引入aa模块，在rust中一个文件名就代表一个模块，创建aa.rs文件
aa.rs
pub fn aa1(){ println!("---aa-----"); }
$ cargo run Compiling crate_path v0.1.0 (/opt/wks/rust_study/crate_path) Finished dev [unoptimized + debuginfo] target(s) in 0.20s Running `target/debug/crate_path` ------------------------------------ ---aa-----
将代码存到不到的目录
src下第一层目录文件结构
aa
aa.rs
main.rs
aa目录下有文件
bb.rs
cc.rs
rust中mod模块与文件名一一对应，存在一个mod aa，就必须得有一个叫aa.rs的文件存在；
若是想在mod aa下代码放到不同的文件中去，拆分成几个文件就有几个mod
但文件中不能再放文件，目录才可以放文件，于是rust就创建一个同名的目录，也叫aa，目录aa下再放其他文件
main.rs
mod aa; fn main() { println!("------------------------------------------------"); aa::bb::bb1(); aa::cc::cc1(); }
aa.rs
pub mod bb;
pub mod cc;
aa/bb.rs
pub fn bb1(){ println!("-----------bb1-----------"); }
aa/cc.rs
pub fn cc1(){ println!("--------------cc1------------"); }
上面是两个可运行的例子，下面是完整的体系式的概念
Packages and Crates
A package is one or more crates that provide a set of functionality. A package contains a Cargo.toml file that describes how to build those crates.
A crate is a binary or library.
src/main.rs is the crate root of a binary crate with the same name as the package.
Likewise, Cargo knows that if the package directory contains src/lib.rs, the package contains a library crate with the same name as the package, and src/lib.rs is its crate root. Cargo passes the crate root files to rustc to build the library or binary.
$ cargo new my-project Created binary (application) `my-project` package $ ls my-project Cargo.toml src $ ls my-project/src main.rs
Here, we have a package that only contains src/main.rs, meaning it only contains a binary crate named my-project. If a package contains src/main.rs and src/lib.rs, it has two crates: a library and a binary, both with the same name as the package. A package can have multiple binary crates by placing files in the src/bin directory: each file will be a separate binary crate.
Defining Modules to Control Scope and Privacy
the use keyword that brings a path into scope; and the pub keyword to make items public. We’ll also discuss the as keyword, external packages, and the glob operator.
. Create a new library named restaurant by running cargo new --lib restaurant;
mod front_of_house {
mod hosting {
fn add_to_waitlist() {}
fn seat_at_table() {}
}
mod serving {
fn take_order() {}
fn serve_order() {}
fn take_payment() {}
}
}
fn main() {}
By using modules, we can group related definitions together and name why they’re related. Programmers using this code would have an easier time finding the definitions they wanted to use because they could navigate the code based on the groups rather than having to read through all the definitions. Programmers adding new functionality to this code would know where to place the code to keep the program organized.
Earlier, we mentioned that src/main.rs and src/lib.rs are called crate roots. The reason for their name is that the contents of either of these two files form a module named crate at the root of the crate’s module structure, known as the module tree.
crate
└── front_of_house
├── hosting
│ ├── add_to_waitlist
│ └── seat_at_table
└── serving
├── take_order
├── serve_order
└── take_payment
Paths for Referring to an Item in the Module Tree
A path can take two forms:
An absolute path starts from a crate root by using a crate name or a literal crate.
A relative path starts from the current module and uses self, super, or an identifier in the current module.
Both absolute and relative paths are followed by one or more identifiers separated by double colons (::).
Bringing Paths into Scope with the use Keyword
创建新项目
aa.rs
mod bb { pub mod bb1{ pub fn bb1_1(){ println!("aa --> bb --> bb1 --> bb1_1"); } pub fn bb1_2(){ println!("-----self ----------------"); self::bb1_1(); } } pub fn bb2(){ println!("aa --> bb --> bb2"); } } //相当于在本crate中提供一个pub方法，供外部调用 use self::bb::bb1::bb1_1 as b1; pub fn aa1(){ b1(); } //让pub bb2在其父mod bb私有的提前下，可供外部程序调用 //bb2本身必须pub pub use self::bb::bb2; //对外提供一个pub模块 pub mod cc { //crate是绝对路径，root crate是main.rs use crate::aa::bb::bb1::bb1_2 as b2; pub fn cc1(){ b2(); } pub mod cc2{ pub fn cc2_1(){ println!("aa --> cc --> cc2 --> cc2_1"); } } }
main.rs
mod aa; use aa::cc::cc2; fn main(){ println!("-----------------------------------"); aa::aa1(); aa::cc::cc1(); aa::bb2(); cc2::cc2_1(); }
输出
$ cargo run Compiling test_lib v0.1.0 (/opt/wks/rust_study/test_lib) Finished dev [unoptimized + debuginfo] target(s) in 0.21s Running `target/debug/test_lib` ----------------------------------- aa --> bb --> bb1 --> bb1_1 -----self ---------------- aa --> bb --> bb1 --> bb1_1 aa --> bb --> bb2 aa --> cc --> cc2 --> cc2_1
标签：bsp earlier lob str like div app reason its
原文地址：https://www.cnblogs.com/perfei/p/13224361.html
