crate and super

Reach from the crate root or parent module with crate and super.

crate and super

Paths can be written as absolute or relative:

crate:: — an absolute path starting from the crate root.
super:: — the parent module (like .. in a file system).
self:: — the current module.

fn kok() -> i32 { 10 }

mod a {
    pub fn ortak() -> i32 { 1 }

    pub mod b {
        pub fn f() -> i32 {
            super::ortak() + crate::kok()   // 1 + 10
        }
    }
}

Which one when?

Between tightly coupled modules, super:: is used; the paths don't break when the code moves together. If something from elsewhere in the project is needed, crate:: is clearer. The same prefixes apply in use declarations:

mod rapor {
    use crate::ayarlar::Ayar;   // from elsewhere in the project
    use super::ortak_bicim;     // from a neighbour
}

Exercise Relative and absolute paths

Write the structure above: fn kok() -> i32 (10) at the root, ortak (1) inside mod a, and inside pub mod b an f returning super::ortak() + crate::kok(). Print the result of a::b::f().

Show example solution

fn kok() -> i32 {
    10
}

mod a {
    pub fn ortak() -> i32 {
        1
    }

    pub mod b {
        pub fn f() -> i32 {
            super::ortak() + crate::kok()
        }
    }
}

fn main() {
    println!("{}", a::b::f());
}

Test yourself

Can a child module call a non-<code>pub</code> function in its parent with <code>super::</code>?
- Only with crate::
- Only in a test module
- Yes; child modules can see their ancestors' private items
- No
Show answer

Yes; child modules can see their ancestors' private items — Privacy is free going upward, not downward. That's why a tests module reaches everything with use super::*;.

Parent module

pub fn f() -> i32 {
    ____::ortak() + crate::kok()
}

Show answer

pub fn f() -> i32 {
    super::ortak() + crate::kok()
}

Prefix and starting point

crate::

Crate root
super::

Parent module
self::

Current module
std::

Standard library

Next lesson: Summary - Modules

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies