Is there a way to use locked standard input and output in a constructor to live as long as the struct you're constructing?

Question

I\'m building a PromptSet that can ask a series of questions in a row. For testing reasons, it allows you to pass a reader and writer instead of using stdin & s

Answer 1

Might be not really the answer to your question, but to a similar problem. Here's my solution.

The main trick here is to call stdin.lock() for every single line.

use std::io;
use std::io::prelude::*;
use std::io::Stdin;

struct StdinWrapper {
    stdin: Stdin,
}

impl Iterator for StdinWrapper {
    type Item = String;

    fn next(&mut self) -> Option {
        let stdin = &self.stdin;
        let mut lines = stdin.lock().lines();
        match lines.next() {
            Some(result) => Some(result.expect("Cannot read line")),
            None => None,
        }
    }
}

/**
 * Callers of this method should not know concrete source of the strings.
 * It could be Stdin, a file, DB, or even aliens from SETI.
 */
fn read() -> Box> {
    let stdin = io::stdin();
    Box::new(StdinWrapper { stdin })
}

fn main() {
    let lines = read();

    for line in lines {
        println!("{}", line);
    }
}