Tracking issue for std::fs::read, read_string, and write

[SimonSapin]

Implemented in #45837

New APIs in std::fs:

pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> { … }
pub fn read_string<P: AsRef<Path>>(path: P) -> io::Result<String> { … }
pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> { ... }

(read_string is based on read_to_string and so returns an error on non-UTF-8 content.)

Before:

use std::fs::File;
use std::io::Read;

let mut bytes = Vec::new();
File::open(filename)?.read_to_end(&mut bytes)?;
do_something_with(bytes)

After:

use std::fs;

do_something_with(fs::read(filename)?)

[JordiPolo]

Implemented, so shouldn't this be closed?

[steveklabnik]

@JordiPolo this issue is tracking their stabilization, not their implementation.

[SimonSapin]

By the way, is there a delay before we should start FCP for stabilization? This is niche enough that I don’t expect to get more feedback just by waiting. I’m not planning to use these functions myself until they’re stable.

[leonardo-m]

Is also adding a lazy iterator on lines a good idea?

[SimonSapin]

@leonardo-m https://doc.rust-lang.org/std/io/trait.BufRead.html#method.lines already exists. Or do you mean adding a convenience function that calls it from a filename? I personally feel less need for that function, but feel free to open a new PR for it.

[leonardo-m]

I meant a convenience function. It's often useful for small script-like programs, tests, benchmarks, online code competitions and games, etc.

[SimonSapin]

@aturon Let’s stabilize?

[sfackler]

@rfcbot fcp merge

[rfcbot]

Team member @sfackler has proposed to merge this. The next step is review by the rest of the tagged teams:

• @BurntSushi
• @Kimundi
• @KodrAus
• @alexcrichton
• @aturon
• @dtolnay
• @sfackler
• @withoutboats

No concerns currently listed.

Once a majority of reviewers approve (and none object), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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[alexcrichton]

This landed less than a month ago, right? Is that a bit rapid for stabilization?

[withoutboats]

Why read_string instead of read_to_string? Seems incorrect to me.

[dtolnay]

I would expect something named read_to_string to take a &mut String argument, like in io::Read.