Trait sp_std::ops::Sub1.0.0[−][src]

pub trait Sub<Rhs = Self> {
    type Output;
    fn sub(self, rhs: Rhs) -> Self::Output;
}
Expand description

The subtraction operator -.

Note that Rhs is Self by default, but this is not mandatory. For example, std::time::SystemTime implements Sub<Duration>, which permits operations of the form SystemTime = SystemTime - Duration.

Examples

Subtractable points

use std::ops::Sub;

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

impl Sub for Point {
    type Output = Self;

    fn sub(self, other: Self) -> Self::Output {
        Self {
            x: self.x - other.x,
            y: self.y - other.y,
        }
    }
}

assert_eq!(Point { x: 3, y: 3 } - Point { x: 2, y: 3 },
           Point { x: 1, y: 0 });

Implementing Sub with generics

Here is an example of the same Point struct implementing the Sub trait using generics.

use std::ops::Sub;

#[derive(Debug, PartialEq)]
struct Point<T> {
    x: T,
    y: T,
}

// Notice that the implementation uses the associated type `Output`.
impl<T: Sub<Output = T>> Sub for Point<T> {
    type Output = Self;

    fn sub(self, other: Self) -> Self::Output {
        Point {
            x: self.x - other.x,
            y: self.y - other.y,
        }
    }
}

assert_eq!(Point { x: 2, y: 3 } - Point { x: 1, y: 0 },
           Point { x: 1, y: 3 });

Associated Types

The resulting type after applying the - operator.

Required methods

Performs the - operation.

Example

assert_eq!(12 - 1, 11);

Implementations on Foreign Types

Returns the difference of self and rhs as a new HashSet<T, S>.

Examples

use std::collections::HashSet;

let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();

let set = &a - &b;

let mut i = 0;
let expected = [1, 2];
for x in &set {
    assert!(expected.contains(x));
    i += 1;
}
assert_eq!(i, expected.len());

Implementors