Mech
带有一个驱动程序,它是一个Named
实体。在运行时,省略的Mech
构造函数会向外部源咨询要使用的特定类型的驱动程序。
trait Named {
fn name(self) -> String;
}
struct Person {
first_name: String,
last_name: String
}
impl Named for Person {
fn name(self) -> String {
format!("{} {}", self.first_name, self.last_name)
}
}
pub struct Mech<'a> {
driver: Box<Named + 'a>,
}
impl<'a> Mech<'a> {
pub fn driver_name(self) -> String {
self.driver.name()
}
}
方法driver_name
将所有权返回到String
,以便在链式调用中进一步使用它(在实际代码中为Command
)。编译失败:
error[E0161]: cannot move a value of type Named + 'a: the size of Named + 'a cannot be statically determined
--> src/lib.rs:22:9
|
22 | self.driver.name()
| ^^^^^^^^^^^
进行特征Sized
会使对象安全失效:
trait Named: Sized {
fn name(self) -> String;
}
↓
error[E0038]: the trait `Named` cannot be made into an object
--> src/lib.rs:17:5
|
17 | driver: Box<Named + 'a>,
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Named` cannot be made into an object
|
= note: the trait cannot require that `Self : Sized`
有没有办法使这种模式发生?
我似乎缺少什么基本的东西吗?
如果这不可能实现,有什么好的解决方法?
答案 0 :(得分:5)
正如编译器所暗示的那样,无法静态确定特征,因为您正在处理动态调度。在这种情况下,可以使用systemctl daemon-reload
systemctl restart logstash
来拥有所有权:
Box<Self>