Struct std::lazy::SyncLazy  [−][src]
pub struct SyncLazy<T, F = fn() -> T> { /* fields omitted */ }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")
}