From 1f9a8a1620a677d668c981a8e6be3ce02ef06cd5 Mon Sep 17 00:00:00 2001 From: Camelid Date: Thu, 5 Nov 2020 00:44:42 -0800 Subject: [PATCH] Add a `std::io::read_to_string` function The equivalent of `std::fs::read_to_string`, but generalized to all `Read` impls. As the documentation on `std::io::read_to_string` says, the advantage of this function is that it means you don't have to create a variable first and it provides more type safety since you can only get the buffer out if there were no errors. If you use `Read::read_to_string`, you have to remember to check whether the read succeeded because otherwise your buffer will be empty. It's friendlier to newcomers and better in most cases to use an explicit return value instead of an out parameter. --- library/std/src/io/mod.rs | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs index dfbf6c3f2444..7a1896e4e590 100644 --- a/library/std/src/io/mod.rs +++ b/library/std/src/io/mod.rs @@ -945,6 +945,33 @@ pub trait Read { } } +/// Convenience function for [`Read::read_to_string`]. +/// +/// This avoids having to create a variable first and it provides more type safety +/// since you can only get the buffer out if there were no errors. (If you use +/// [`Read::read_to_string`] you have to remember to check whether the read succeeded +/// because otherwise your buffer will be empty.) +/// +/// # Examples +/// +/// ```no_run +/// #![feature(io_read_to_string)] +/// +/// # use std::io; +/// fn main() -> io::Result<()> { +/// let stdin = io::read_to_string(&mut io::stdin())?; +/// println!("Stdin was:"); +/// println!("{}", stdin); +/// Ok(()) +/// } +/// ``` +#[unstable(feature = "io_read_to_string", issue = "80218")] +pub fn read_to_string(reader: &mut R) -> Result { + let mut buf = String::new(); + reader.read_to_string(&mut buf)?; + Ok(buf) +} + /// A buffer type used with `Read::read_vectored`. /// /// It is semantically a wrapper around an `&mut [u8]`, but is guaranteed to be