Trait std::ops::Sub1.0.0[−][src]

#[lang = "sub"]

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

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, PartialEq)]
struct Point {
    x: i32,
    y: i32,
}

impl Sub for Point {
    type Output = Point;

    fn sub(self, other: Point) -> Point {
        Point {
            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 });Run

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 = Point<T>;

    fn sub(self, other: Point<T>) -> Point<T> {
        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 });Run

Associated Types

The resulting type after applying the - operator.

Required Methods

Performs the - operation.

Implementors