Struct scale_info::prelude::sync::LazyLock
source · pub struct LazyLock<T, F = fn() -> T> { /* private fields */ }
🔬This is a nightly-only experimental API. (
lazy_cell
)Expand description
A value which is initialized on the first access.
This type is a thread-safe LazyCell
, and can be used in statics.
Examples
#![feature(lazy_cell)]
use std::collections::HashMap;
use std::sync::LazyLock;
static HASHMAP: LazyLock<HashMap<i32, String>> = LazyLock::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§
source§impl<T, F> LazyLock<T, F>where
F: FnOnce() -> T,
impl<T, F> LazyLock<T, F>where F: FnOnce() -> T,
sourcepub const fn new(f: F) -> LazyLock<T, F>
🔬This is a nightly-only experimental API. (lazy_cell
)
pub const fn new(f: F) -> LazyLock<T, F>
lazy_cell
)Creates a new lazy value with the given initializing function.
sourcepub fn into_inner(this: LazyLock<T, F>) -> Result<T, F>
🔬This is a nightly-only experimental API. (lazy_cell_consume
)
pub fn into_inner(this: LazyLock<T, F>) -> Result<T, F>
lazy_cell_consume
)Consumes this LazyLock
returning the stored value.
Returns Ok(value)
if Lazy
is initialized and Err(f)
otherwise.
Examples
#![feature(lazy_cell)]
#![feature(lazy_cell_consume)]
use std::sync::LazyLock;
let hello = "Hello, World!".to_string();
let lazy = LazyLock::new(|| hello.to_uppercase());
assert_eq!(&*lazy, "HELLO, WORLD!");
assert_eq!(LazyLock::into_inner(lazy).ok(), Some("HELLO, WORLD!".to_string()));
sourcepub fn force(this: &LazyLock<T, F>) -> &T
🔬This is a nightly-only experimental API. (lazy_cell
)
pub fn force(this: &LazyLock<T, F>) -> &T
lazy_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(lazy_cell)]
use std::sync::LazyLock;
let lazy = LazyLock::new(|| 92);
assert_eq!(LazyLock::force(&lazy), &92);
assert_eq!(&*lazy, &92);
Trait Implementations§
impl<T, F> RefUnwindSafe for LazyLock<T, F>where T: RefUnwindSafe + UnwindSafe, F: UnwindSafe,
impl<T, F> Sync for LazyLock<T, F>where T: Sync + Send, F: Send,
impl<T, F> UnwindSafe for LazyLock<T, F>where T: UnwindSafe, F: UnwindSafe,
Auto Trait Implementations§
impl<T, F> Send for LazyLock<T, F>where F: Send, T: Send,
impl<T, F> Unpin for LazyLock<T, F>where F: Unpin, T: Unpin,
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-formatted.source§impl<T> Pipe for Twhere
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