From a1e1b5c3fb599ea8ea7ec7f785f3cc35c3be9666 Mon Sep 17 00:00:00 2001
From: Andy Russell <arussell123@gmail.com>
Date: Mon, 18 Jun 2018 23:24:29 -0400
Subject: [PATCH 1/2] rework `LineWriter` example
The original example didn't check the return value of `write()`, didn't
flush the writer, and didn't properly demonstrate the buffering.
Fixes #51621.
---
src/libstd/io/buffered.rs | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index ee297d3783e52..ed085d5c0df8e 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -738,7 +738,7 @@ impl<W> fmt::Display for IntoInnerError<W> {
/// reducing the number of actual writes to the file.
///
/// ```no_run
-/// use std::fs::File;
+/// use std::fs::{self, File};
/// use std::io::prelude::*;
/// use std::io::LineWriter;
///
@@ -752,17 +752,31 @@ impl<W> fmt::Display for IntoInnerError<W> {
/// let file = File::create("poem.txt")?;
/// let mut file = LineWriter::new(file);
///
-/// for &byte in road_not_taken.iter() {
-/// file.write(&[byte]).unwrap();
-/// }
+/// file.write_all(b"I shall be telling this with a sigh")?;
+///
+/// // No bytes are written until a newline is encountered (or
+/// // the internal buffer is filled).
+/// assert_eq!(fs::read_to_string("poem.txt")?.as_bytes(), b"");
+/// file.write_all(b"\n")?;
+/// assert_eq!(
+/// fs::read_to_string("poem.txt")?.as_bytes(),
+/// &b"I shall be telling this with a sigh\n"[..],
+/// );
///
-/// // let's check we did the right thing.
-/// let mut file = File::open("poem.txt")?;
-/// let mut contents = String::new();
+/// // Write the rest of the poem.
+/// file.write_all(b"Somewhere ages and ages hence:
+/// Two roads diverged in a wood, and I -
+/// I took the one less traveled by,
+/// And that has made all the difference.")?;
///
-/// file.read_to_string(&mut contents)?;
+/// // The last line of the poem doesn't end in a newline, so
+/// // we have to flush or drop the `LineWriter` to finish
+/// // writing.
+/// file.flush()?;
///
-/// assert_eq!(contents.as_bytes(), &road_not_taken[..]);
+/// // Confirm the whole poem was written.
+/// let mut poem = fs::read_to_string("poem.txt")?;
+/// assert_eq!(poem.as_bytes(), &road_not_taken[..]);
/// Ok(())
/// }
/// ```
@@ -862,7 +876,7 @@ impl<W: Write> LineWriter<W> {
///
/// The internal buffer is written out before returning the writer.
///
- // # Errors
+ /// # Errors
///
/// An `Err` will be returned if an error occurs while flushing the buffer.
///
From c12a75742485dcc3db7b0f374e78f090c323830d Mon Sep 17 00:00:00 2001
From: Andy Russell <arussell123@gmail.com>
Date: Wed, 11 Jul 2018 14:39:22 -0400
Subject: [PATCH 2/2] simplify assertions
---
src/libstd/io/buffered.rs | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index ed085d5c0df8e..189569683a9cf 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -756,11 +756,11 @@ impl<W> fmt::Display for IntoInnerError<W> {
///
/// // No bytes are written until a newline is encountered (or
/// // the internal buffer is filled).
-/// assert_eq!(fs::read_to_string("poem.txt")?.as_bytes(), b"");
+/// assert_eq!(fs::read_to_string("poem.txt")?, "");
/// file.write_all(b"\n")?;
/// assert_eq!(
-/// fs::read_to_string("poem.txt")?.as_bytes(),
-/// &b"I shall be telling this with a sigh\n"[..],
+/// fs::read_to_string("poem.txt")?,
+/// "I shall be telling this with a sigh\n",
/// );
///
/// // Write the rest of the poem.
@@ -775,8 +775,7 @@ impl<W> fmt::Display for IntoInnerError<W> {
/// file.flush()?;
///
/// // Confirm the whole poem was written.
-/// let mut poem = fs::read_to_string("poem.txt")?;
-/// assert_eq!(poem.as_bytes(), &road_not_taken[..]);
+/// assert_eq!(fs::read("poem.txt")?, &road_not_taken[..]);
/// Ok(())
/// }
/// ```