<分区>
我想编写一个函数来解析字符串并返回实现特征对象的几个结构之一,该特征对象允许分发对实现结构的引用。用例是从确定使用哪个实现的配置文件中读取字符串。代码如下所示:
trait Foo<'a> {
fn get(&'a self) -> &'a i32;
}
struct Bar {
data: i32,
}
impl<'a> Foo<'a> for Bar {
fn get(&'a self) -> &'a i32 {
&self.data
}
}
struct Baz {
data: i32,
}
impl<'a> Foo<'a> for Baz {
fn get(&'a self) -> &'a i32 {
&self.data
}
}
fn get_foo(foo: &str) -> Box<dyn Foo> {
let split = foo.splitn(2, "+").collect::<Vec<_>>();
let data = i32::from_str_radix(split[1], 10).unwrap();
if foo.starts_with("bar") {
Box::new(Bar { data })
} else {
Box::new(Baz { data })
}
}
fn main() {
let foo = get_foo("bar+0");
println!("Foo: {}", foo.get());
}
但是,当我这样做时,出现了这个错误:
error[E0597]: `*foo` does not live long enough
--> src/main.rs:38:25
|
38 | println!("Foo: {}", foo.get());
| ^^^ borrowed value does not live long enough
39 | }
| - `*foo` dropped here while still borrowed
|
= note: values in a scope are dropped in the opposite order they are created
这在 Rust 中可以做到吗?