Trait One 

pub trait One: Sized {
    // Required methods
    fn one() -> Self;
    fn set_one(&mut self);
    fn is_one(&self) -> bool;
}

Defines a multiplicative identity element for Self.

A pure identity-value trait, decoupled from Mul for the same reason as Zero: 1 is equally the identity under division (a / 1 = a), so privileging Mul is arbitrary. Consumers state what they need (T: One + Mul, T: One + Div, …); full numeric code takes Num.

Laws

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

Required Methods

fn one() -> Self

Returns the multiplicative identity element of Self, 1.

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.

fn set_one(&mut self)

Sets self to the multiplicative identity element of Self, 1.

fn is_one(&self) -> bool

Returns true if self is equal to the multiplicative identity.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl One for f32

fn one() -> f32

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for f64

fn one() -> f64

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for i8

fn one() -> i8

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for i16

fn one() -> i16

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for i32

fn one() -> i32

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for i64

fn one() -> i64

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for i128

fn one() -> i128

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for isize

fn one() -> isize

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for u8

fn one() -> u8

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for u16

fn one() -> u16

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for u32

fn one() -> u32

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for u64

fn one() -> u64

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for u128

fn one() -> u128

fn set_one(&mut self)

fn is_one(&self) -> bool

impl One for usize

fn one() -> usize

fn set_one(&mut self)

fn is_one(&self) -> bool

impl<T: One> One for Saturating<T>

where Saturating<T>: Mul<Output = Saturating<T>>,

fn set_one(&mut self)

fn one() -> Self

fn is_one(&self) -> bool

impl<T: One> One for Wrapping<T>

where Wrapping<T>: Mul<Output = Wrapping<T>>,

fn set_one(&mut self)

fn one() -> Self

fn is_one(&self) -> bool

Implementors