Structs

A struct can include .. to indicate that you want to use a copy of some other struct for some of the values. For example:

struct Point3d {
    x: i32,
    y: i32,
    z: i32,
}

let mut point = Point3d { x: 0, y: 0, z: 0 };
point = Point3d { y: 1, .. point };

This gives point a new y, but keeps the old x and z values. It doesn’t have to be the same struct either, you can use this syntax when making new ones, and it will copy the values you don’t specify:

let origin = Point3d { x: 0, y: 0, z: 0 };
let point = Point3d { z: 1, x: 2, .. origin };