Trait num_traits::identities::One

pub trait One: Sized + Mul<Self, Output = Self> {
    fn one() -> Self;

    fn is_one(&self) -> bool
    where
        Self: PartialEq,
    { ... }
}

Defines a multiplicative identity element for Self.

Required Methods

fn one() -> Self

Returns the multiplicative identity element of Self, 1.

Laws

a * 1 = a       ∀ a ∈ Self
1 * a = a       ∀ a ∈ Self

Purity

This function should return the same result at all times regardless of external mutable state, for example values stored in TLS or in static muts.

Provided Methods

fn is_one(&self) -> bool where
    Self: PartialEq, 

Returns true if self is equal to the multiplicative identity.

For performance reasons, it's best to implement this manually. After a semver bump, this method will be required, and the where Self: PartialEq bound will be removed.

Implementations on Foreign Types

impl One for usize

fn one() -> usize

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for u8

fn one() -> u8

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for u16

fn one() -> u16

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for u32

fn one() -> u32

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for u64

fn one() -> u64

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for isize

fn one() -> isize

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for i8

fn one() -> i8

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for i16

fn one() -> i16

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for i32

fn one() -> i32

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for i64

fn one() -> i64

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for f32

fn one() -> f32

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl One for f64

fn one() -> f64

fn is_one(&self) -> bool where
    Self: PartialEq, 

impl<T: One> One for Wrapping<T> where
    Wrapping<T>: Mul<Output = Wrapping<T>>, 

fn one() -> Self

fn is_one(&self) -> bool where
    Self: PartialEq, 

Implementors