Struct async_once_cell::ConstLazy

pub struct ConstLazy<T, F> { /* private fields */ }

A value which is initialized on the first access.

Note: This structure may be larger in size than Lazy, but it does not allocate on the heap until it is first polled, so is suitable for initializing statics.

Implementations

impl<T, F> ConstLazy<T, F>

pub const fn new(future: F) -> Self

Creates a new lazy value with the given initializing future.

pub const fn with_value(value: T) -> Self

Creates an already-initialized lazy value.

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

Gets the value without blocking or starting the initialization.

pub fn try_get_mut(&mut self) -> Option<&mut T>

Gets the value without blocking or starting the initialization.

This requires mutable access to self, so rust’s aliasing rules prevent any concurrent access and allow violating the usual rules for accessing this cell.

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

Gets the value if it was set.

impl<T, F> ConstLazy<T, F> where
    F: Future<Output = T> + Send + 'static, 

pub async fn get(&self) -> &T

Forces the evaluation of this lazy value and returns a reference to the result.

This is equivalent to the Future impl on &ConstLazy, but is explicit and may be simpler to call. This will panic if the initializing closure panics or has panicked.

Trait Implementations

impl<T: Debug, F: Debug> Debug for ConstLazy<T, F>

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

Formats the value using the given formatter.

impl<'a, T, F> Future for &'a ConstLazy<T, F> where
    F: Future<Output = T> + Send + 'static, 

type Output = &'a T

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<&'a T>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.