相关疑难解决方法(0)

如何Option从调用者的特定生命周期中提取引用并将其传回？

具体而言,我想借用参照Box<Foo>从Bar一个具有Option<Box<Foo>>在其中.我以为我能做到:

impl Bar {
    fn borrow(&mut self) -> Result<&Box<Foo>, BarErr> {
        match self.data {
            Some(e) => Ok(&e),
            None => Err(BarErr::Nope),
        }
    }
}

......但结果是:

error: `e` does not live long enough
  --> src/main.rs:17:28
   |
17 |             Some(e) => Ok(&e),
   |                            ^ does not live long enough
18 |             None => Err(BarErr::Nope),
19 |         }
   |         - borrowed value only lives until here
   |
note: borrowed value must be valid for the …