如何創建捕獲 Rc 的 wasm_bindgen 閉包<RefCell<_> &gt; 不搬出去？

Question

我的狀態需要通過 JavaScript 回調多次改變（這是一個游戲，所以來自用戶的輸入需要修改游戲狀態）。 我似乎無法弄清楚該怎么做。 這是我能想到的最簡單的例子，它證明了我遇到的問題：

#[wasm_bindgen(start)]
pub fn run() {
    let data = Rc::new(RefCell::new(vec![0]));
    let closure = Closure::wrap(Box::new(&mut || {
        data.borrow_mut().push(0);
        console_log!("{data:?}");
    }) as Box<dyn FnMut()>);

    closure.forget();
}

我認為使用Rc會使data在使用期間保持有效，但我收到此錯誤：

error[E0716]: temporary value dropped while borrowed
  --> src/lib.rs:19:47
   |
19 |        let closure = Closure::wrap(Box::new(&mut || {
   |   _________________________________-_____________^
   |  |_________________________________|
   | ||
20 | ||         data.borrow_mut().push(0);
21 | ||         console_log!("{data:?}");
22 | ||     }) as Box<dyn FnMut()>);
   | ||     ^-                     - temporary value is freed at the end of this statement
   | ||_____||
   |  |_____|cast requires that borrow lasts for `'static`
   |        creates a temporary which is freed while still in use

error[E0597]: `data` does not live long enough
  --> src/lib.rs:20:9
   |
19 |       let closure = Closure::wrap(Box::new(&mut || {
   |                                   -             -- value captured here
   |  _________________________________|
   | |
20 | |         data.borrow_mut().push(0);
   | |         ^^^^ borrowed value does not live long enough
21 | |         console_log!("{data:?}");
22 | |     }) as Box<dyn FnMut()>);
   | |______- cast requires that `data` is borrowed for `'static`
...
25 |   }
   |   - `data` dropped here while still borrowed

我該如何解決這個問題？

Answer 1

Rc可以讓它足夠活，但目前你正在借用Rc本身，它在run()結束時被銷毀。 您需要克隆它，並將克隆移動到閉包中：

#[wasm_bindgen(start)]
pub fn run() {
    let data = Rc::new(RefCell::new(vec![0]));
    let closure = Closure::wrap(Box::new({
        let data = Rc::clone(&data);
        &mut move || {
            data.borrow_mut().push(0);
            console_log!("{data:?}");
        }
    }) as Box<dyn FnMut()>);

    closure.forget();
}

您還不需要借用閉包本身，這就是“借用時臨時值下降”錯誤的原因。 替換&mut move || { &mut move || {只需move || { move || { .