# Struct std::sync::OnceState 1.51.0[−][src]

    pub struct OnceState { /* fields omitted */ }

State yielded to `Once::call_once_force()`’s closure parameter. The state can be used to query the poison status of the `Once`.

## Implementations

### `impl OnceState`[src]

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

Returns `true` if the associated `Once` was poisoned prior to the invocation of the closure passed to `Once::call_once_force()`.

# Examples

A poisoned `Once`:

    use std::sync::Once;
    use std::thread;

    static INIT: Once = Once::new();

    // poison the once
    let handle = thread::spawn(|| {
        INIT.call_once(|| panic!());
    });
    assert!(handle.join().is_err());

    INIT.call_once_force(|state| {
        assert!(state.is_poisoned());
    });

Run

An unpoisoned `Once`:

    use std::sync::Once;

    static INIT: Once = Once::new();

    INIT.call_once_force(|state| {
        assert!(!state.is_poisoned());
    });

Run

## Trait Implementations

### `impl Debug for OnceState`[src]

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result`[src]

Formats the value using the given formatter. Read more

## Auto Trait Implementations

### `impl !RefUnwindSafe for OnceState`[src]

### `impl Send for OnceState`[src]

### `impl !Sync for OnceState`[src]

### `impl Unpin for OnceState`[src]

### `impl UnwindSafe for OnceState`[src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W`
`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W`
`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T`[src]

#### `pub fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U`[src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.