Rust Package Manager — Cargo

All the dependencies required by the Rust language can be managed by cargo which also acts as the build tool. If any dependency is missing from the project, cargo will automatically download the package and build the library for the project.

Same as git, to create an empty project that can be managed by cargo, one only needs to enter the following command:

$ cargo new "some_project" # or cargo new from the current directory.
$ cd ./some_project

In addition, a typical cargo-created project will contain the following files and directories:

.
├── Cargo.lock
├── Cargo.toml
├── src
└── target

• Cargo.toml: This file is in the TOML (Tom’s Obvious, Minimal Language) format, which is Cargo’s configuration format.

  [package]
  name = "hello_cargo"
  version = "0.1.0"
  edition = "2021"
  
  [dependencies]
  // Some dependencies
  

  The first line, [package], is a section heading that indicates that the following statements are configuring a package. As we add more information to this file, we’ll add other sections. The last line, [dependencies], is the start of a section for you to list any of your project’s dependencies. In Rust, packages of code are referred to as crates.

• Cargo.lock contains exact information about your dependencies. It is maintained by Cargo and should NOT be manually edited.

• Source code goes in the src directory.

• The default executable file is src/main.rs.

  • Other executables can be placed in src/bin/.

• Benchmarks go in the benches directory.

• Examples go in the examples directory.

• Integration tests go in the tests directory.

You could build the project by

$ cargo build
cargo build
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s

You could run the project by

$ cargo run

cargo run        
   Compiling ch1_hello_rust v0.1.0 (/home/hiroki/rust-learning/ch1_hello_rust)
    Finished dev [unoptimized + debuginfo] target(s) in 0.56s
     Running `target/debug/ch1_hello_rust` # This is where the targetl locates.
Hello, world!

• We can build a project without producing a binary to check for errors using cargo check.
• Instead of saving the result of the build in the same directory as our code, Cargo stores it in the target/debug directory.