Struct double_checked_cell::DoubleCheckedCell

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

A thread-safe lazily initialized cell.

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

Methods

impl<T> DoubleCheckedCell<T>

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);

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

Borrows the value if the cell is initialized.

Panics

Panics if the cell is poisoned.

Examples

use double_checked_cell::DoubleCheckedCell;

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

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

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

Panics

Panics if the cell is poisoned.

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);

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 if the cell is poisoned.

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));

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));

Trait Implementations

impl<T> Default for DoubleCheckedCell<T>

fn default() -> DoubleCheckedCell<T>

Returns the "default value" for a type.

impl<T: Debug> Debug for DoubleCheckedCell<T>

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

Formats the value using the given formatter.

impl<T> From<T> for DoubleCheckedCell<T>

fn from(t: T) -> DoubleCheckedCell<T>

Performs the conversion.

impl<T: Sync> Sync for DoubleCheckedCell<T>

impl<T> RefUnwindSafe for DoubleCheckedCell<T>