diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs index ee297d3783e52..189569683a9cf 100644 --- a/src/libstd/io/buffered.rs +++ b/src/libstd/io/buffered.rs @@ -738,7 +738,7 @@ impl fmt::Display for IntoInnerError { /// 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 +752,30 @@ impl fmt::Display for IntoInnerError { /// 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")?, ""); +/// file.write_all(b"\n")?; +/// assert_eq!( +/// fs::read_to_string("poem.txt")?, +/// "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. +/// assert_eq!(fs::read("poem.txt")?, &road_not_taken[..]); /// Ok(()) /// } /// ``` @@ -862,7 +875,7 @@ impl LineWriter { /// /// 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. ///