Struct caffe2_imports::LazyLock
source · pub struct LazyLock<T, F = fn() -> T> { /* private fields */ }
🔬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 LazyCell
, and can be used in statics.
Examples
#![feature(once_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. (once_cell
)
pub const fn new(f: F) -> LazyLock<T, F>
once_cell
)Creates a new lazy value with the given initializing function.
sourcepub fn force(this: &LazyLock<T, F>) -> &T
🔬This is a nightly-only experimental API. (once_cell
)
pub fn force(this: &LazyLock<T, F>) -> &T
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::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,
Blanket Implementations§
§impl<T> Pointable for T
impl<T> Pointable for T
§impl<SS, SP> SupersetOf<SS> for SPwhere
SS: SubsetOf<SP>,
impl<SS, SP> SupersetOf<SS> for SPwhere SS: SubsetOf<SP>,
§fn to_subset(&self) -> Option<SS>
fn to_subset(&self) -> Option<SS>
The inverse inclusion map: attempts to construct
self
from the equivalent element of its
superset. Read more§fn is_in_subset(&self) -> bool
fn is_in_subset(&self) -> bool
Checks if
self
is actually part of its subset T
(and can be converted to it).§fn to_subset_unchecked(&self) -> SS
fn to_subset_unchecked(&self) -> SS
Use with care! Same as
self.to_subset
but without any property checks. Always succeeds.§fn from_subset(element: &SS) -> SP
fn from_subset(element: &SS) -> SP
The inclusion map: converts
self
to the equivalent element of its superset.