Package Structure

package - is the projects which happens when performing cargo new command.
- crates - every package contains
  - crate types
    - binary crate - code to execute
    - library crate - code to be use by others
  - modules - crates contains modules with privacy rules
  - workspaces - for big projects ans allows to store interrelated packages

Crates

In every project there are two main files main.rs and lib.rs. For a binary project, the main.rs file is the entry point of the program. For a library project, the lib.rs file is the entry point of the library. If there are multiple source files in the project there are different ways to intregrate them into your project.

Binary crate

A project containing main.rs file in the root of the project scr/ directory. Cargo creates a binary crate with the binary name the same as the package name defined in Cargo.toml.

To create more binary crates. Add files with the crate name in a new subfolder src/bin/

cargo new <packagename>

Structure

file structure:

└── src/
   ├── main.rs
   ├── config.rs
   └── helpers.rs

main.rs

mod config;
mod helpers;

fn main() {
    config::read_config();
}

config.rs

crate::helpers::do_something();

pub fn read_config() {
    do_something();
    println!("Reading config");
}

helpers.rs

pub fn do_something() {
    println!("Doing something");
}

Library crate

A project containing lib.rs file in the root of the project scr/ directory. Cargo creates a library crate with the library name the same as the package name defined in `Cargo.toml``.

cargo new --lib <packagename>

Structure

including a main.rs

file structure:

rustlib/
└── src/
   ├── main.rs
   ├── lib.rs
   ├── config.rs
   └── helpers.rs

lib.rs

pub mod config;
pub mod helpers;

main.rs

user rust_lib::config;

fn main() {
    config::read_config();
}

config.rs

crate::helpers::do_something();

pub fn read_config() {
    do_something();
    println!("Reading config");
}

helpers.rs

pub fn do_something() {
    println!("Doing something");
}

Rules

A package needs to have at least one crate.
A package need to have 0 or 1 library crate.
A package can have any number of binary crates.