Impl and Self

What is Self, not in a philosophical sense, but what is Self in rusts world?

We create a simple Struct which defines a bool and an int.

struct RandomInfo {
    some_bool: bool,
    some_int: i32,
}

We can then implement the struct as a type:

impl RandomInfo {
    fn new() -> RandomInfo {
        RandomInfo {
            some_bool: true,
            some_int: 42,
        }
    }
}

However, we don't actually need to specify the type, the compiler is able to infer the type itself, so we can instead use Self

impl RandomInfo {
    fn new() -> Self {
        Self {
            some_bool: true,
            some_int: 42,
        }
    }
}

Putting it all together

struct RandomInfo {
    some_bool: bool,
    some_int: i32,
}

impl RandomInfo {
    fn new() -> Self {
        Self {
            some_bool: true,
            some_int: 42,
        }
    }
}

fn main() {
    let info = RandomInfo::new();
    println!("some_bool: {}", info.some_bool);
    println!("some_int: {}", info.some_int);
}