Struct spin::lazy::Lazy

source · [−]
pub struct Lazy<T, F = fn() -> T, R = Spin> { /* private fields */ }
Available on crate feature lazy only.
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

use std::collections::HashMap;
use spin::Lazy;

static HASHMAP: Lazy<HashMap<i32, String>> = Lazy::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

Creates a new lazy value with the given initializing function.

Retrieves a mutable pointer to the inner data.

This is especially useful when interfacing with low level code or FFI where the caller explicitly knows that it has exclusive access to the inner data. Note that reading from this pointer is UB until initialized or directly written to.

Forces the evaluation of this lazy value and returns a reference to result. This is equivalent to the Deref impl, but is explicit.

Examples
use spin::Lazy;

let lazy = Lazy::new(|| 92);

assert_eq!(Lazy::force(&lazy), &92);
assert_eq!(&*lazy, &92);

Trait Implementations

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.

Dereferences the value.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.