Add, Mul, …
Operator overloading is implemented via traits in std::ops:
#[derive(Debug, Copy, Clone)]
struct Point { x: i32, y: i32 }
impl std::ops::Add for Point {
type Output = Self;
fn add(self, other: Self) -> Self {
Self {x: self.x + other.x, y: self.y + other.y}
}
}
fn main() {
let p1 = Point { x: 10, y: 20 };
let p2 = Point { x: 100, y: 200 };
println!("{:?} + {:?} = {:?}", p1, p2, p1 + p2);
}
Discussion points:
- You could implement
Add
for&Point
. In which situations is that useful?- Answer:
Add:add
consumesself
. If typeT
for which you are overloading the operator is notCopy
, you should consider overloading the operator for&T
as well. This avoids unnecessary cloning on the call site.
- Answer:
- Why is
Output
an associated type? Could it be made a type parameter?- Short answer: Type parameters are controlled by the caller, but associated types (like
Output
) are controlled by the implementor of a trait.
- Short answer: Type parameters are controlled by the caller, but associated types (like