问题描述
我想从 TCPStream
中读取一行,向其中写入另一行,然后重复.问题是 BufReader::new
拥有我的 TCPStream
变量:
I want to read a line from a TCPStream
, write another line to it, and then repeat. The issue is that BufReader::new
takes ownership of my TCPStream
variable:
let stream = ...; // TCPStream
let reader = BufReader::new(stream); // moved its value
// can't use stream here anymore
对此有什么简单的解决方案?
What is a simple solution to this?
推荐答案
解决方案:使用引用.
let mut stream = ...;
let reader = BufReader::new(&stream);
let writer = BufWriter::new(&stream);
说明
如果我们仔细看看 BufReader::new
,我们会发现它接受一个 R
类型的参数 inner
,其中 R
只是任何实现 Read
的类型:
Explanation
If we take a closer look at BufReader::new
, we see that it takes an argument inner
of type R
, where R
is just any type that implements Read
:
impl<R: Read> BufReader<R> {
pub fn new(inner: R) -> BufReader<R> { ... }
}
然后我们看一下Read
,看看这个实现:
We then take a look at Read
and see this implementation:
impl<'a> Read for &'a TcpStream
所以我们可以只传递一个对 new
函数的引用,就像这样:
So we can just pass a reference to the new
function, like so:
let reader = BufReader::new(&stream);
我们将对 BufWriter
和 Write
做同样的事情,并会看到确实有这个实现:
We will do the same for BufWriter
and Write
and will see that indeed there is this implementation:
impl<'a> Write for &'a TcpStream
所以我们可以再次使用不可变引用来创建 BufWriter
.
So we can, again, use an immutable reference to create the BufWriter
.
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