Rust Programming By Example

Copy types

Some types are not moved when we assigned a value of these types to another variable. This is the case for basic types such as integers. For instance, the following code is perfectly valid:

let num1 = 42;
let num2 = num1;
println!("{}", num1);

We can still use num1 even thought we assigned it to num2. This is because the basic types implement a special marker: Copy. Copy types are copied instead of moved.

We can make our own types Copy by adding derive to them:

#[derive(Clone, Copy)]
struct Point {
    x: i32,
    y: i32,
}

Since Copy requires Clone, we also implement the latter for our Point type. We cannot derive Copy for a type containing a value that does not implement Copy. Now, we can use a Point without having to bother with references: ...