--- minutes: 10 --- # use, super, self A module can bring symbols from another module into scope with `use`. You will typically see something like this at the top of each module: ```rust,editable use std::collections::HashSet; use std::process::abort; ``` ## Paths Paths are resolved as follows: 1. As a relative path: - `foo` or `self::foo` refers to `foo` in the current module, - `super::foo` refers to `foo` in the parent module. 2. As an absolute path: - `crate::foo` refers to `foo` in the root of the current crate, - `bar::foo` refers to `foo` in the `bar` crate.
- It is common to "re-export" symbols at a shorter path. For example, the top-level `lib.rs` in a crate might have ```rust,ignore mod storage; pub use storage::disk::DiskStorage; pub use storage::network::NetworkStorage; ``` making `DiskStorage` and `NetworkStorage` available to other crates with a convenient, short path. - For the most part, only items that appear in a module need to be `use`'d. However, a trait must be in scope to call any methods on that trait, even if a type implementing that trait is already in scope. For example, to use the `read_to_string` method on a type implementing the `Read` trait, you need to `use std::io::Read`. - The `use` statement can have a wildcard: `use std::io::*`. This is discouraged because it is not clear which items are imported, and those might change over time.