Trait genio::Write
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[src]
pub trait Write { type WriteError; type FlushError; fn write(&mut self, buf: &[u8]) -> Result<usize, Self::WriteError>; fn flush(&mut self) -> Result<(), Self::FlushError>; fn write_all(&mut self, buf: &[u8]) -> Result<(), Self::WriteError> { ... } fn size_hint(&mut self, min: usize, max: Option<usize>) { ... } }
A trait for objects which are byte-oriented sinks.
Implementors of the Write
trait are sometimes called 'writers'.
Writers are defined by two required types WriteError
, FlushError
and methods, write()
and flush()
:
The write()
method will attempt to write some data into the object, returning how many
bytes were successfully written.
The flush()
method is useful for adaptors and explicit buffers themselves for ensuring that
all buffered data has been pushed out to the 'true sink'.
Writers are intended to be composable with one another. Many implementors throughout
genio
take and provide types which implement the Write
trait.
Associated Types
type WriteError
Value of this type is returned when write()
fails.
It's highly recommended to use Void
from void
crate if read()
can never fail.
type FlushError
Value of this type is returned when flush()
fails.
In case of low-level writers flush often does nothing and therefore doesn't return error,
so this type might be Void.
It's highly recommended to use Void
from void
crate if read()
can never fail.
Required Methods
fn write(&mut self, buf: &[u8]) -> Result<usize, Self::WriteError>
Write a buffer into this object, returning how many bytes were written.
This function will attempt to write the entire contents of buf
, but the entire write may
not succeed, or the write may also generate an error. A call to write
represents at most
one attempt to write to any wrapped object.
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.
Errors
Each call to write may generate an WriteError
indicating that the operation could not be
completed. If an error is returned then no bytes in the buffer were written to this writer.
It is not considered an error if the entire buffer could not be written to this writer.
fn flush(&mut self) -> Result<(), Self::FlushError>
Flush this output stream, ensuring that all intermediately buffered contents reach their destination.
Errors
It is considered an error if not all bytes could be written due to I/O errors or EOF being reached.
Provided Methods
fn write_all(&mut self, buf: &[u8]) -> Result<(), Self::WriteError>
Attempts to write an entire buffer into this Write
.
fn size_hint(&mut self, min: usize, max: Option<usize>)
Hints the writer how much bytes will be written after call to this function.
At least min
bytes should be written after the call to this function and if max
is
Some(x)
than at most x
bytes should be written.
Call to this function might enable some optimizations (e.g. pre-allocating buffer of appropriate size). The implementors must not rely on this call to provide correct values or on this function being called at all! (Especially they must not cause undefined behavior.) However, performance might be arbitrarilly degraded in case min value is incorrect.
By default this function does nothing.
Implementors
impl Write for Vec<u8>
impl Write for std::io::util::Sink
impl<W: Write> Write for GenioWrite<W>
impl<T: Write> Write for GenioIo<T>
impl<W: Write> Write for WriteTrunc<W>
impl<W> Write for Restarting<W> where
W: Write,
W::WriteError: IntoIntrError,
W::FlushError: IntoIntrError,impl Write for genio::util::Sink