Struct once_cell::race::OnceBox

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pub struct OnceBox<T> { /* private fields */ }
Expand description

A thread-safe cell which can be written to only once.

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impl<T> OnceBox<T>

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pub const fn new() -> OnceBox<T>

Creates a new empty cell.

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pub fn get(&self) -> Option<&T>

Gets a reference to the underlying value.

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pub fn set(&self, value: Box<T>) -> Result<(), Box<T>>

Sets the contents of this cell to value.

Returns Ok(()) if the cell was empty and Err(value) if it was full.

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pub fn get_or_init<F>(&self, f: F) -> &T
where F: FnOnce() -> Box<T>,

Gets the contents of the cell, initializing it with f if the cell was empty.

If several threads concurrently run get_or_init, more than one f can be called. However, all threads will return the same value, produced by some f.

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pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E>
where F: FnOnce() -> Result<Box<T>, E>,

Gets the contents of the cell, initializing it with f if the cell was empty. If the cell was empty and f failed, an error is returned.

If several threads concurrently run get_or_init, more than one f can be called. However, all threads will return the same value, produced by some f.

Trait Implementations§

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impl<T> Debug for OnceBox<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<T> Default for OnceBox<T>

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fn default() -> Self

Returns the “default value” for a type. Read more
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impl<T> Drop for OnceBox<T>

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<T: Sync + Send> Sync for OnceBox<T>

Auto Trait Implementations§

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impl<T> RefUnwindSafe for OnceBox<T>
where T: RefUnwindSafe,

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impl<T> Send for OnceBox<T>
where T: Send,

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impl<T> Unpin for OnceBox<T>

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impl<T> UnwindSafe for OnceBox<T>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.