Struct sexually_transmitted_disease::lazy::SyncLazy [−][src]
pub struct SyncLazy<T, F = fn() -> T> { /* fields omitted */ }
🔬 This is a nightly-only experimental API. (
once_cell
)Expand description
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
)
🔬 This is a nightly-only experimental API. (
once_cell
)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);