Struct lazyonce::LazyOnce

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

Wrapper type for lazy initialization

Implementations

impl<T> LazyOnce<T>

pub fn new() -> Self

pub fn get(&self, f: impl FnOnce() -> T) -> &T

Get cached value, or if no value has been cached yet, compute it using the callback function.

If the callback panics, any use of the cell will panic, too.

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

Get cached value or None if the cell is still empty

Does not wait if the cell is being filled in

pub fn try_get_for( &self, duration: Duration, f: impl FnOnce() -> T ) -> Option<&T>

Get cached value or None if the cell is still empty

It waits for the cell to be filled in only for a limited time, and falls back to None on timeout

pub fn get_mut(&mut self, f: impl FnOnce() -> T) -> &mut T

Get mutable reference to the cached value, or if no value has been cached yet, compute it using the callback function.

pub fn expect(&self, s: &str) -> &T

Assume the value has already been computed. Crash if the cell is empty.

Panics

If get() hasn’t been called yet.

pub fn expect_mut(&mut self, s: &str) -> &mut T

Assume the value has already been computed. Crash if the cell is empty.

Panics

If get() hasn’t been called yet.

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

Return computed value or None if the cell is empty.

Unlike try_get this returns an owned value, permanently “unwrapping” the cell.