# [−][src]Struct std::sync::OnceState

    pub struct OnceState { /* fields omitted */ }

🔬 This is a nightly-only experimental API. (`once_poison` #33577)

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

## Methods

### `impl OnceState`[src]

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

🔬 This is a nightly-only experimental API. (`once_poison` #33577)

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

# Examples

A poisoned `Once`:

    #![feature(once_poison)]

    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.poisoned());
    });Run

An unpoisoned `Once`:

    #![feature(once_poison)]

    use std::sync::Once;

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

    INIT.call_once_force(|state| {
        assert!(!state.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 UnwindSafe for OnceState`

### `impl RefUnwindSafe for OnceState`

### `impl Unpin for OnceState`

### `impl Send for OnceState`

### `impl Sync for OnceState`

## Blanket Implementations

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

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

Performs the conversion.

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

#### `type Error = !`

The type returned in the event of a conversion error.

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

Performs the conversion.

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

#### `fn into(self) -> U`[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.

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

Performs the conversion.

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

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

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

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

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

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

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