Struct std::lazy::SyncLazy

pub struct SyncLazy<T, F = fn() -> T> { /* fields omitted */ }
???? This is a nightly-only experimental API. (once_cell #74465)

A value which is initialized on the first access.

This type is a thread-safe Lazy, and can be used in statics.

Examples

#![feature(once_cell)]

use std::collections::HashMap;

use std::lazy::SyncLazy;

static HASHMAP: SyncLazy<HashMap<i32, String>> = SyncLazy::new(|| {
    println!("initializing");
    let mut m = HashMap::new();
    m.insert(13, "Spica".to_string());
    m.insert(74, "Hoyten".to_string());
    m
});

fn main() {
    println!("ready");
    std::thread::spawn(|| {
        println!("{:?}", HASHMAP.get(&13));
    }).join().unwrap();
    println!("{:?}", HASHMAP.get(&74));

    // Prints:
    //   ready
    //   initializing
    //   Some("Spica")
    //   Some("Hoyten")
}

Implementations

???? This is a nightly-only experimental API. (once_cell #74465)

Creates a new lazy value with the given initializing function.

???? This is a nightly-only experimental API. (once_cell #74465)

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

Examples

#![feature(once_cell)]

use std::lazy::SyncLazy;

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

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

Trait Implementations

Formats the value using the given formatter. Read more

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

The resulting type after dereferencing.

Dereferences the value.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/lazy/struct.SyncLazy.html