main/
main.rs

1extern crate dispatch;
2
3use std::io;
4use std::process::exit;
5use dispatch::{Queue, QueuePriority};
6
7/// Prompts for a number and adds it to the given sum.
8///
9/// Reading from stdin is done on the given queue.
10/// All printing is performed on the main queue.
11/// Repeats until the user stops entering numbers.
12fn prompt(mut sum: i32, queue: Queue) {
13    queue.clone().exec_async(move || {
14        let main = Queue::main();
15        // Print our prompt on the main thread and wait until it's complete
16        main.exec_sync(|| {
17            println!("Enter a number:");
18        });
19
20        // Read the number the user enters
21        let mut input = String::new();
22        io::stdin().read_line(&mut input).unwrap();
23
24        if let Ok(num) = input.trim().parse::<i32>() {
25            sum += num;
26            // Print the sum on the main thread and wait until it's complete
27            main.exec_sync(|| {
28                println!("Sum is {}\n", sum);
29            });
30            // Do it again!
31            prompt(sum, queue);
32        } else {
33            // Bail if no number was entered
34            main.exec_async(|| {
35                println!("Not a number, exiting.");
36                exit(0);
37            });
38        }
39    });
40}
41
42fn main() {
43    // Read from stdin on a background queue so that the main queue is free
44    // to handle other events. All printing still occurs through the main
45    // queue to avoid jumbled output.
46    prompt(0, Queue::global(QueuePriority::Default));
47
48    unsafe {
49        dispatch::ffi::dispatch_main();
50    }
51}
main/main.rs

main/
main.rs
