除了在每个闭包之前克隆它之外,还有其他选择可以在多个闭包中共享 Arc 吗? [英] Is there another option to share an Arc in multiple closures besides cloning it before each closure?
本文介绍了除了在每个闭包之前克隆它之外,还有其他选择可以在多个闭包中共享 Arc 吗?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有这样的事情:
use std::sync::Arc;
fn main() {
let arc = Arc::new(42);
move || { arc.clone() };
move || { arc.clone() };
}
我得到:
error[E0382]: capture of moved value: `arc`
--> src/main.rs:6:19
|
5 | move || { arc.clone() };
| ------- value moved (into closure) here
6 | move || { arc.clone() };
| ^^^ value captured here after move
|
= note: move occurs because `arc` has type `std::sync::Arc<i32>`, which does not implement the `Copy` trait
我明白为什么我会得到这个:在 arc
传递给闭包之前没有调用 clone
.我可以通过在函数中定义每个闭包并在将 Arc
传递给闭包之前克隆它来解决这个问题,但还有其他选择吗?
I understand why I am getting this: the clone
isn't called before arc
is passed to the closure. I can fix this by defining each closure in a function and clone the Arc
before passing it to the closure, but is there another option?
推荐答案
没有办法解决.在将 Arc
用于闭包之前,您应该克隆它.常见的模式是将克隆的 Arc
重新绑定到嵌套作用域中的相同名称:
There is no way around it. You should clone the Arc
before it is used in a closure. The common pattern is to re-bind the cloned Arc
to the same name in a nested scope:
use std::sync::Arc;
fn main() {
let arc = Arc::new(42);
{
let arc = arc.clone();
move || { /* do something with arc */ };
}
{
let arc = arc.clone();
move || { /* do something else with arc */ };
}
}
这通常与 thread::spawn()
一起完成:
This is usually done together with thread::spawn()
:
use std::sync::{Arc, Mutex};
use std::thread;
const NUM_THREADS: usize = 4;
fn main() {
let arc = Arc::new(Mutex::new(42));
for _ in 0..NUM_THREADS {
let arc = arc.clone();
thread::spawn(move || {
let mut shared_data = arc.lock().unwrap();
*shared_data += 1;
});
}
}
这篇关于除了在每个闭包之前克隆它之外,还有其他选择可以在多个闭包中共享 Arc 吗?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文