Book: Tasks example out of date

[jlgerber]

Here is the tasks example:

use async_std::fs::File;
use async_std::task;

async fn read_file(path: &str) -> Result<String, io::Error> {
    let mut file = File::open(path).await?;
    let mut contents = String::new();
    file.read_to_string(&mut contents).await?;
    contents
}

fn main() {
    let reader_task = task::spawn(async {
        let result = read_file("data.csv").await;
        match result {
            Ok(s) => println!("{}", s),
            Err(e) => println!("Error reading file: {:?}", e)
        }
    });
    println!("Started task!");
    task::block_on(reader_task);
    println!("Stopped task!");
}

But it does not work. File does not have a read_to_string method seemingly.

Here is what I had to do to get it to work:

async fn read_file(path: &str) -> io::Result<String> {
    //let mut file = File::open(path).await?;
    fs::read_to_string(path).await
}

fn main() {
    let reader_task = task::spawn(async {
        let result = read_file("data.csv").await;
        match result {
            Ok(s) => println!("{}", s),
            Err(e) => println!("Error reading file: {:?}", e),
        }
    });
    println!("Started task!");
    task::block_on(reader_task);
    println!("Stopped task!");
}

[skade]

Hi, this is similar to the stdlib: read_to_string is a method of io::Read, so it must be in scope. I updated the example to make the imports visible.

Thanks for the report!