pub struct SyncLazy<T, F = fn() -> T> { /* private fields */ }
🔬 This is a nightly-only experimental API. (
once_cell
#74465)
Expand description
A value which is initialized on the first access.
This type is a thread-safe Lazy
, and can be used in statics.
#![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));
}
Run
🔬 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.
#![feature(once_cell)]
use std::lazy::SyncLazy;
let lazy = SyncLazy::new(|| 92);
assert_eq!(SyncLazy::force(&lazy), &92);
assert_eq!(&*lazy, &92);
Run
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.
impl<T> Any for T where
T: 'static + ?Sized,
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
impl<T, U> Into<U> for T where
U: From<T>,
The type returned in the event of a conversion error.
The type returned in the event of a conversion error.