Struct double_checked_cell::DoubleCheckedCell

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pub struct DoubleCheckedCell<T> { /* private fields */ }

Expand description

A thread-safe lazily initialized cell.

The cell is immutable once it is initialized. See the module-level documentation for more.

Implementations

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impl<T> DoubleCheckedCell<T>

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pub fn new() -> DoubleCheckedCell<T>

Creates a new uninitialized DoubleCheckedCell.

Examples

use double_checked_cell::DoubleCheckedCell;

let cell = DoubleCheckedCell::<u32>::new();
assert_eq!(cell.get(), None);

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

Borrows the value if the cell is initialized.

Examples

use double_checked_cell::DoubleCheckedCell;

let cell = DoubleCheckedCell::from("hello");
assert_eq!(cell.get(), Some(&"hello"));

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pub fn get_or_init<F>(&self, init: F) -> &Twhere
F: FnOnce() -> T,

Borrows the value if the cell is initialized or initializes it from a closure.

Panics

Panics or deadlocks when trying to access the cell from the initilization closure.

Examples

use double_checked_cell::DoubleCheckedCell;

let cell = DoubleCheckedCell::new();

// Initialize the cell.
let value = cell.get_or_init(|| 1 + 2);
assert_eq!(*value, 3);

// The cell is now immutable.
let value = cell.get_or_init(|| 42);
assert_eq!(*value, 3);

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

Borrows the value if the cell is initialized or attempts to initialize it from a closure.

Errors

Forwards any error from the closure if the cell is not yet initialized. The cell then remains uninitialized.

Panics

Panics or deadlocks when trying to access the cell from the initilization closure.

Examples

use double_checked_cell::DoubleCheckedCell;

let cell = DoubleCheckedCell::new();

let result = cell.get_or_try_init(|| "not an integer".parse());
assert!(result.is_err());

let result = cell.get_or_try_init(|| "42".parse());
assert_eq!(result, Ok(&42));

let result = cell.get_or_try_init(|| "irrelevant".parse());
assert_eq!(result, Ok(&42));

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pub fn into_inner(self) -> Option<T>

Unwraps the value.

Examples

use double_checked_cell::DoubleCheckedCell;

let cell = DoubleCheckedCell::from(42);
let contents = cell.into_inner();
assert_eq!(contents, Some(42));