Read and Write

Using Read and BufRead, you can abstract over u8 sources:

1. use std::io::{BufRead, BufReader, Read, Result};

3. fn count_lines<R: Read>(reader: R) -> usize {
4. let buf_reader = BufReader::new(reader);
5. buf_reader.lines().count()
6. }

8. fn main() -> Result<()> {
9. let slice: &[u8] = b"foo\nbar\nbaz\n";
10. println!("lines in slice: {}", count_lines(slice));

12. let file = std::fs::File::open(std::env::current_exe()?)?;
13. println!("lines in file: {}", count_lines(file));
14. Ok(())
15. }

Similarly, Write lets you abstract over u8 sinks:

1. use std::io::{Result, Write};

3. fn log<W: Write>(writer: &mut W, msg: &str) -> Result<()> {
4. writer.write_all(msg.as_bytes())?;
5. writer.write_all("\n".as_bytes())
6. }

8. fn main() -> Result<()> {
9. let mut buffer = Vec::new();
10. log(&mut buffer, "Hello")?;
11. log(&mut buffer, "World")?;
12. println!("Logged: {:?}", buffer);
13. Ok(())
14. }