Weak

class Weak<T>

use gc::{Weak};

A handle that refers to a value without keeping it alive, made by weak.

upgrade returns the value while something else still keeps it alive, and None once a collection has freed it. Use it for registries and caches that must not extend lifetimes. A Weak cannot be sent to another thread.

Examples#

use gc::{weak, upgrade, Weak};
use tests::assert;
let data = Vec::from([1, 2]);
let w: Weak<Vec<int>> = weak(data);
let alive = match upgrade(w) {
    Option::Some(v) => v.len() == 2,
    Option::None => false,
};
assert!(alive && data.len() == 2);

See also#

• gc::weak
• gc::upgrade
• Root: A strong pin that keeps a value alive, made by root.