Struct once_cell::unsync::Lazy

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

A value which is initialized on the first access.

Example

use once_cell::unsync::Lazy;

let lazy: Lazy<i32> = Lazy::new(|| {
    println!("initializing");
    92
});
println!("ready");
println!("{}", *lazy);
println!("{}", *lazy);

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

Methods

impl<T, F: Fn() -> T> Lazy<T, F>

pub fn new(init: F) -> Lazy<T, F>

Creates a new lazy value with the given initializing function.

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

Forces the evaluation of this lazy value and returns a reference to result. This is equivalent to the Deref impl, but is explicit.

Example

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 + Fn() -> T> Debug for Lazy<T, F>

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

Formats the value using the given formatter.

impl<T, F: Fn() -> T> Deref for Lazy<T, F>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.