E.g. in the code below, ThreeD is an enum which can either be a Point or a Vector. The function cross is intended to calculate the cross product of two Vectors, and panic if either argument is a Point.

In order to calculate the result I need the x, y and z components of both the lhs and the rhs. As it stands however the second match will obscure the x,y and z members from the first match.

One option is to explicitly assign the x, y, and z members to temporary variables, immediately after the first let statement, but this feels horribly klunky.

pub fn cross(lhs: ThreeD, rhs: ThreeD) -> ThreeD {
    if let Vector { x, y, z } = lhs {
        let lhs_x = x;    // I DON'T LIKE THIS APPROACH!
        let lhs_y = y;    //
        let lhs_z = z;    //

        if let Vector { x, y, z } = rhs {
            // dummy calc here - I know this is wrong ;-)
            Vector { x: lhs_x * x, y: lhs_y * y, z: lhs_z * z }
        } else {
            panic!("Cannot calculate cross product with a point")
        }
    } else {
        panic!("Cannot calculate cross product against a point")
    }
}

>Solution :

You can bind to a different name within the pattern using this syntax:

if let Vector { x: lhs_x, y: lhs_y, z: lhs_z } = lhs {