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bufwriter::WriterPanicked: Provide panicking example 

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
This commit is contained in:
Ian Jackson 2020-12-12 12:34:48 +00:00
parent 381763185e
commit 7fab9cb8ac
1 changed files with 24 additions and 0 deletions
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24
library/std/src/io/buffered/bufwriter.rs
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@ -324,6 +324,30 @@ impl<W: Write> BufWriter<W> {
#[unstable(feature = "bufwriter_into_raw_parts", issue = "none")]
/// Error returned for the buffered data from `BufWriter::into_raw_parts`, when the underlying
/// writer has previously panicked. Contains the (possibly partly written) buffered data.
///
/// # Example
///
/// ```
/// #![feature(bufwriter_into_raw_parts)]
/// use std::io::{self, BufWriter, Write};
/// use std::panic::{catch_unwind, AssertUnwindSafe};
///
/// struct PanickingWriter;
/// impl Write for PanickingWriter {
/// fn write(&mut self, buf: &[u8]) -> io::Result<usize> { panic!() }
/// fn flush(&mut self) -> io::Result<()> { panic!() }
/// }
///
/// let mut stream = BufWriter::new(PanickingWriter);
/// write!(stream, "some data").unwrap();
/// let result = catch_unwind(AssertUnwindSafe(|| {
/// stream.flush().unwrap()
/// }));
/// assert!(result.is_err());
/// let (recovered_writer, buffered_data) = stream.into_raw_parts();
/// assert!(matches!(recovered_writer, PanickingWriter));
/// assert_eq!(buffered_data.unwrap_err().into_inner(), b"some data");
/// ```
pub struct WriterPanicked {
buf: Vec<u8>,
}