[英]Rust trait field lifetime
我认为这是我显然想念的东西,但是这里有..
use std::io;
pub trait Source<'a, T> {
fn push(&self, t: T) -> io::Result<()>;
fn link(&mut self, sink: &dyn Sink<'a, T>) -> io::Result<()>;
}
pub trait Sink<'a, T> {
fn push(&self, t: T) -> io::Result<()>;
fn link(&mut self, source: &dyn Source<T>) -> io::Result<()>;
}
pub struct SyncSource<'a, T> {
sink: Option<&'a dyn Sink<'a, T>>,
}
impl<'a, T> SyncSource<'a, T> {
pub fn new() -> SyncSource<'a, T> {
SyncSource {
sink: None,
}
}
}
impl<'a, T> Source<'a, T> for SyncSource<'a, T> {
fn push(&self, t: T) -> io::Result<()> {
match self.sink {
Some(sink) => sink.push(t),
None => Err(io::Error::new(io::ErrorKind::NotConnected, "no sink")),
}
}
fn link(&mut self, sink: &dyn Sink<'a, T>) -> io::Result<()> {
self.sink = Some(sink);
Ok(())
}
}
pub struct SyncSink<'a, T> {
source: Option<&'a dyn Source<'a, T>>,
}
impl<'a, T> SyncSink<'a, T> {
pub fn new() -> SyncSink<'a, T> {
SyncSink {
source: None,
}
}
}
impl<'a, T> Sink<'a, T> for SyncSink<'a, T> {
fn push(&self, t: T) -> io::Result<()> {
match self.source {
Some(source) => source.push(t),
None => Err(io::Error::new(io::ErrorKind::NotConnected, "no source")),
}
}
fn link(&mut self, source: &dyn Source<T>) -> io::Result<()> {
self.source = Some(source);
Ok(())
}
}
我阅读了关于生命周期的 rustlang 书籍章节,但无法真正理解这里出了什么问题。 我要做的是构建一个基本的 pipe 和过滤器架构。 源知道它的接收器,接收器知道它的源,因此我想存储对对象的引用。 显然,这里有一个终身问题。
我首先考虑引入生命周期'a
来表示源/接收器的寿命与它所链接的 object 一样长。 这不起作用。 现在我在想我可能需要一个比 'a 寿命更长的生命 b 并以某种方式将其混入其中,但正如你所看到的,这就是我感到困惑的地方。
你快到了:
use std::io;
pub trait Source<'a, T> {
fn push(&self, t: T) -> io::Result<()>;
// Make sure the references themselves have the 'a lifetime marker
fn link(&'a mut self, sink: &'a dyn Sink<'a, T>) -> io::Result<()>;
}
pub trait Sink<'a, T> {
fn push(&self, t: T) -> io::Result<()>;
// Make sure the references themselves have the 'a lifetime marker
fn link(&'a mut self, source: &'a dyn Source<'a, T>) -> io::Result<()>;
}
pub struct SyncSource<'a, T> {
sink: Option<&'a dyn Sink<'a, T>>,
}
impl<'a, T> SyncSource<'a, T> {
pub fn new() -> SyncSource<'a, T> {
SyncSource {
sink: None,
}
}
}
impl<'a, T> Source<'a, T> for SyncSource<'a, T> {
fn push(&self, t: T) -> io::Result<()> {
match self.sink {
Some(sink) => sink.push(t),
None => Err(io::Error::new(io::ErrorKind::NotConnected, "no sink")),
}
}
// Now match the lifetime definitions that is defined in the trait
fn link(&'a mut self, sink: &'a dyn Sink<'a, T>) -> io::Result<()> {
self.sink = Some(sink);
Ok(())
}
}
pub struct SyncSink<'a, T> {
source: Option<&'a dyn Source<'a, T>>,
}
impl<'a, T> SyncSink<'a, T> {
pub fn new() -> SyncSink<'a, T> {
SyncSink {
source: None,
}
}
}
impl<'a, T> Sink<'a, T> for SyncSink<'a, T> {
fn push(&self, t: T) -> io::Result<()> {
match self.source {
Some(source) => source.push(t),
None => Err(io::Error::new(io::ErrorKind::NotConnected, "no source")),
}
}
// Now match the lifetime definitions that is defined in the trait
fn link(&'a mut self, source: &'a dyn Source<'a, T>) -> io::Result<()> {
self.source = Some(source);
Ok(())
}
}
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