[−][src]Trait async_std::io::Write
Allows writing to a byte stream.
This trait is an async version of std::io::Write
.
While it is currently not possible to implement this trait directly, it gets implemented
automatically for all types that implement futures::io::AsyncWrite
.
Required methods
fn write<'a>(&'a mut self, buf: &'a [u8]) -> ImplFuture<'a, Result<usize>> where
Self: Unpin,
Self: Unpin,
Writes some bytes into the byte stream.
Returns the number of bytes written from the start of the buffer.
If the return value is Ok(n)
then it must be guaranteed that 0 <= n <= buf.len()
. A
return value of 0
typically means that the underlying object is no longer able to accept
bytes and will likely not be able to in the future as well, or that the buffer provided is
empty.
Examples
use async_std::fs::File; use async_std::prelude::*; let mut f = File::create("a.txt").await?; let n = f.write(b"hello world").await?;
fn flush(&mut self) -> ImplFuture<Result<()>> where
Self: Unpin,
Self: Unpin,
Flushes the stream to ensure that all buffered contents reach their destination.
Examples
use async_std::fs::File; use async_std::prelude::*; let mut f = File::create("a.txt").await?; f.write_all(b"hello world").await?; f.flush().await?;
Provided methods
fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> ImplFuture<'a, Result<usize>> where
Self: Unpin,
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> ImplFuture<'a, Result<usize>> where
Self: Unpin,
Like write
, except that it writes from a slice of buffers.
Data is copied from each buffer in order, with the final buffer read from possibly being
only partially consumed. This method must behave as a call to write
with the buffers
concatenated would.
The default implementation calls write
with either the first nonempty buffer provided,
or an empty one if none exists.
fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> ImplFuture<'a, Result<()>> where
Self: Unpin,
Self: Unpin,
Writes an entire buffer into the byte stream.
This method will continuously call write
until there is no more data to be written or
an error is returned. This method will not return until the entire buffer has been
successfully written or such an error occurs.
Examples
use async_std::fs::File; use async_std::prelude::*; let mut f = File::create("a.txt").await?; f.write_all(b"hello world").await?;