The pub keyword is used to expose paths with Rust. When you mark a module, struct, enum, function, or method with the pub keyword, you make it accessible to other modules. For example, let's say you have a module called `front_of_house` with a submodule called `hosting`. The `hosting` submodule contains a function called `add_to_waitlist()`. If you want to make the `add_to_waitlist()` function accessible to other modules, you would mark it with the pub keyword.
mod front_of_house {
pub mod hosting {
pub fn add_to_waitlist() {}
}
}
Now, any module that can access the `front_of_house` module can also access the `hosting` submodule and the `add_to_waitlist()` function.
The pub keyword can also be used to make paths relative. For example, if you have a function called `eat_at_restaurant()` in the `front_of_house` module, you could use the following code to call the `add_to_waitlist()` function:
pub fn eat_at_restaurant() {
front_of_house::hosting::add_to_waitlist();
}
The `front_of_house::hosting` path is a relative path that starts from the `eat_at_restaurant()` function's module. Because the `hosting` submodule is marked with the pub keyword, the relative path is valid and the `add_to_waitlist()` function can be called.
The pub keyword is a powerful tool that can be used to control the visibility of your code. By marking paths with the pub keyword, you can make your code accessible to other modules and ensure that your public API is consistent.
- Keep the binary crate as small as possible. The binary crate should only contain the code that is necessary to start an executable that calls code with the library crate. This will make it easier for other projects to benefit from the most functionality that the package provides.
- Define the module tree in src/lib.rs. This will make it easy to find and use the public API of the library crate.
- Use the name of the package to start paths in the binary crate. This will make it clear that the binary crate is using the library crate's public API.
- Design a good API. The API of the library crate should be easy to use and understand. This will make it more likely that other projects will want to use your package.
