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0 pointsraggi2y ago0 comments

good catch. feeding it the error output of rustc it then produces:

    use std::fs::File;
    use std::io::{self, Read};

    fn read_file_character_by_character(path: &str) -> io::Result<()> {
        let mut file = File::open(path)?;
        let mut contents = String::new();

        file.read_to_string(&mut contents)?;

        for c in contents.chars() {
            println!("{}", c);
        }

        Ok(())
    }

    fn main() {
        let path = "path/to/your/file.txt";

        if let Err(e) = read_file_character_by_character(path) {
            eprintln!("Error reading file: {}", e);
        }
    }

0 comments

phaer2y ago

But this doesn't read the file char-by-char, but uses buffering to read it into a string

scottlamb2y ago

What would you expect? There's no OS API for "read one character", except in say ASCII where 1 byte = 1 code point = 1 character. And it'd be hideously inefficient anyway. So you either loop over getting the next N bytes and getting all complete characters so far (with some extra complexity around characters that cross chunk boundaries) or you read the whole thing into a single buffer and iterate the characters. This code does the latter. If this tool doesn't have the ability to respond by asking requirements questions, I'd consider either choice valid.

Of course, in real life, I do expect to get requirements questions back from an engineer when I assign a task. Seems more practical than anticipating everything up-front into the perfect specification/prompt. Why shouldn't I expect the same from an LLM-based tool? Are any of them set up to do that?

1letterunixname2y ago

There most certainly is getwchar() and fgetwc()/getwc() on anything that's POSIX C95, so that's more or less everything that's not a vintage antique.

Reading individual UTF-8 codepoints is a trivial exercise if byte width getchar() were available, and portable C code to do so would be able to run on anything made after 1982. IIRC, they don't teach how to write portable C code in Comp Sci programs anymore and it's a shame.

Never read a file completely into memory at once unless there is zero chance of it being a huge file because this is an obvious DoS vector and waste of resources.

1 more reply

1letterunixname2y ago

A few notes:

- It should be generating `path: impl AsRef<Path>` to be properly generic.

- It's not setting a nonzero exit code on error.

- Edge case handling is a vital property for production-usable tools at scale. I'm wondering if it can yet special case situations such as creating a conditional compilation version for Linux that uses the splice syscall when the arguments are 2 file handles.

deathanatos2y ago

On errors, it exits with success.

j / k navigate · click thread line to collapse

0 comments

phaer2y ago

But this doesn't read the file char-by-char, but uses buffering to read it into a string

scottlamb2y ago

1letterunixname2y ago

There most certainly is getwchar() and fgetwc()/getwc() on anything that's POSIX C95, so that's more or less everything that's not a vintage antique.

Never read a file completely into memory at once unless there is zero chance of it being a huge file because this is an obvious DoS vector and waste of resources.

1 more reply

1letterunixname2y ago

A few notes:

- It should be generating `path: impl AsRef<Path>` to be properly generic.

- It's not setting a nonzero exit code on error.

deathanatos2y ago

On errors, it exits with success.

j / k navigate · click thread line to collapse