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Rust by example - http://rustbyexample.com/bounds.html issues
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use std::ops::{Add, Sub, Mul}; | |
#[derive(Show, Copy)] | |
struct Vec2<T> { | |
x: T, | |
y: T, | |
} | |
// Apply bound to `T` at first instance of `T`. `T` | |
// must implement the `Add` trait. | |
impl<T: Add<T, Output = T>> Add<Vec2<T>> | |
for Vec2<T> { | |
type Output = Vec2<T>; | |
fn add(self, rhs: Vec2<T>) -> Vec2<T> { | |
Vec2 { | |
// `x` and `y` are of type `T`, and implement the `add` method | |
x: self.x.add(rhs.x), | |
// The sugary `+` operator can also be used | |
y: self.y + rhs.y, | |
} | |
} | |
} | |
// Bound: `T` must implement the `Sub` trait | |
impl<T> Sub<Vec2<T>> for Vec2<T> | |
where T: Sub<T, Output = T> { | |
type Output = Vec2<T>; | |
fn sub(self, rhs: Vec2<T>) -> Vec2<T> { | |
Vec2 { | |
x: self.x - rhs.x, | |
y: self.y - rhs.y, | |
} | |
} | |
} | |
// Bound: `T` must implement *both* the `Add` trait and the `Mul` trait | |
impl<T> Vec2<T> | |
where T: Add<T, Output = T> + Mul<T, Output = T> { | |
fn dot(self, rhs: Vec2<T>) -> T { | |
(self.x * rhs.x) + (self.y * rhs.y) | |
} | |
} | |
fn main() { | |
// Floats implement the `Add`, `Mul` and `Sub` traits | |
let v1 = Vec2 { x: 1.2_f32, y: 3.4 }; | |
let v2 = Vec2 { x: 5.6_f32, y: 7.8 }; | |
println!("{} + {} = {}", v1, v2, v1 + v2); | |
println!("{} - {} = {}", v1, v2, v1 - v2); | |
println!("{} â‹… {} = {}", v1, v2, v1.dot(v2)); | |
// Error! `char` doesn't implement the `Add` trait | |
//println!("{}", Vec2 { x: ' ', y: 'b' } + Vec2 { x: 'c', y: 'd' }); | |
// FIXME ^ Comment out this line | |
} |
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Vec2 { x: 1.2, y: 3.4 } + Vec2 { x: 5.6, y: 7.8 } = Vec2 { x: 6.8, y: 11.200001 } | |
Vec2 { x: 1.2, y: 3.4 } - Vec2 { x: 5.6, y: 7.8 } = Vec2 { x: -4.4, y: -4.4 } | |
Vec2 { x: 1.2, y: 3.4 } â‹… Vec2 { x: 5.6, y: 7.8 } = 33.240002 |
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