# [−] [src] Trait num_traits::identities::One

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

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

Defines a multiplicative identity element for `Self`.

# 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 mut`s.

Loading content...

## Provided methods

### `fn set_one(&mut self)`

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

### `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.

Loading content...

## Implementations on Foreign Types

### `impl One for usize` [src]

#### `fn one() -> usize` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for u8` [src]

#### `fn one() -> u8` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for u16` [src]

#### `fn one() -> u16` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for u32` [src]

#### `fn one() -> u32` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for u64` [src]

#### `fn one() -> u64` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for u128` [src]

#### `fn one() -> u128` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for isize` [src]

#### `fn one() -> isize` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for i8` [src]

#### `fn one() -> i8` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for i16` [src]

#### `fn one() -> i16` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for i32` [src]

#### `fn one() -> i32` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for i64` [src]

#### `fn one() -> i64` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for i128` [src]

#### `fn one() -> i128` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for f32` [src]

#### `fn one() -> f32` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl One for f64` [src]

#### `fn one() -> f64` [src]

#### `fn is_one(&self) -> bool` [src]

### `impl<T: One> One for Wrapping<T> where
Wrapping<T>: Mul<Output = Wrapping<T>>,` [src]

#### `fn set_one(&mut self)` [src]

#### `fn one() -> Self` [src]

Loading content...

## Implementors

Loading content...

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)