由于双重借用，无法将 self 作为回调参数传递 [英] Cannot pass self as callback parameter due to double borrowing

问题描述

我正在尝试调用保存在结构中的闭包，但我也想将该结构作为参数传递给闭包.这是具体的一段代码.

I'm trying to call closure that was saved inside a struct but I'd also like to pass the struct as an argument to the closure. Here's the specific piece of code.

pub fn react(&mut self) -> &mut Button {
   if let Some(ref mut c) = self.click_callback {
            c(self);
    }
    self
}

注意 self 是一个 Button 而 self.click_callback 是一个 Option>

Note that self is a Button and self.click_callback is an Option<Box<Fn(&mut Button)>>

因此，根据我的理解，if let"借用 self 直到其作用域结束，但是当我尝试将 self 作为参数传递时，它会尝试再次借用它.我可以做些什么来避免这种双重借用尝试?

So from what I understand the "if let" borrows self until its scopes ends, but then when I try to pass self as an argument it attempts to borrow it again. Is there anything specific I can do that will avoid this double borrow attempt?

推荐答案

最简单的解决方案是将回调从 self 中分离出来，如下所示:

The simplest solution is to break the callback out from self, like so:

let callback = self.click_callback.take();
if let Some(ref mut c) = callback {
    c(self);
}
self.click_callback = callback;
self

这会暂时将 click_callback 替换为 None，因此您必须在完成后将其放回原处.

This temporarily replaces click_callback with None, hence why you have to put it back when you're done.

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