Struct once_cell::unsync::Lazy[][src]

pub struct Lazy<T, F = fn() -> T> { /* fields omitted */ }

A value which is initialized on the first access.


use once_cell::unsync::Lazy;

let lazy: Lazy<i32> = Lazy::new(|| {
println!("{}", *lazy);
println!("{}", *lazy);

// Prints:
//   ready
//   initializing
//   92
//   92


impl<T, F> Lazy<T, F>[src]

pub const fn new(init: F) -> Lazy<T, F>[src]

Creates a new lazy value with the given initializing function.


use once_cell::unsync::Lazy;

let hello = "Hello, World!".to_string();

let lazy = Lazy::new(|| hello.to_uppercase());

assert_eq!(&*lazy, "HELLO, WORLD!");

pub fn into_value(this: Lazy<T, F>) -> Result<T, F>[src]

Consumes this Lazy returning the stored value.

Returns Ok(value) if Lazy is initialized and Err(f) otherwise.

impl<T, F: FnOnce() -> T> Lazy<T, F>[src]

pub fn force(this: &Lazy<T, F>) -> &T[src]

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

This is equivalent to the Deref impl, but is explicit.


use once_cell::unsync::Lazy;

let lazy = Lazy::new(|| 92);

assert_eq!(Lazy::force(&lazy), &92);
assert_eq!(&*lazy, &92);

Trait Implementations

impl<T: Debug, F> Debug for Lazy<T, F>[src]

impl<T: Default> Default for Lazy<T>[src]

fn default() -> Lazy<T>[src]

Creates a new lazy value using Default as the initializing function.

impl<T, F: FnOnce() -> T> Deref for Lazy<T, F>[src]

type Target = T

The resulting type after dereferencing.

impl<T, F: FnOnce() -> T> DerefMut for Lazy<T, F>[src]

impl<T, F: RefUnwindSafe> RefUnwindSafe for Lazy<T, F> where
    OnceCell<T>: RefUnwindSafe

Auto Trait Implementations

impl<T, F> Send for Lazy<T, F> where
    F: Send,
    T: Send

impl<T, F = fn() -> T> !Sync for Lazy<T, F>

impl<T, F> Unpin for Lazy<T, F> where
    F: Unpin,
    T: Unpin

impl<T, F> UnwindSafe for Lazy<T, F> where
    F: UnwindSafe,
    T: UnwindSafe

Blanket Implementations

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

impl<T> Borrow<T> for T where
    T: ?Sized

impl<T> BorrowMut<T> for T where
    T: ?Sized

impl<T> From<T> for T[src]

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

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

type Error = Infallible

The type returned in the event of a conversion error.

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

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

The type returned in the event of a conversion error.