rust - 选择动态创建的 channel

Question

我有:

use std::collections::{DList, Deque, TreeMap};
use std::comm::{Select, Handle};

fn main() {
    let mut list = DList::new();
    let mut handles = TreeMap::new();

    let select = Select::new();

    for i in range(0, 3i) {

        // Create channel
        let (tx, rx) = channel();

        // Move receiver inside dlist
        list.push_front(rx);

        // Get the mut ref from the dlist
        let mut nrx = list.front_mut().unwrap();

        let handle = select.handle(nrx);
        let id = handle.id();
        handles.insert(id, handle);

        // Get the mut ref from the map and add to select
        unsafe { handles.find_mut(&id).unwrap().add(); }

        spawn(proc() {
            // Work with the channel
            let sender = tx;
        });

    }

    loop {
        let selected = select.wait();
        println!("Selected channel id: {}", selected);
    }

}

我得到的错误是:

<anon>:21:22: 21:40 error: cannot infer an appropriate lifetime for lifetime parameter 'a in function call due to conflicting requirements
<anon>:21         let handle = select.handle(nrx);
                               ^~~~~~~~~~~~~~~~~~
<anon>:21:22: 21:28 note: first, the lifetime must be contained by the expression at 21:21...
<anon>:21         let handle = select.handle(nrx);
                               ^~~~~~
<anon>:21:22: 21:28 note: ...so that automatically reference is valid at the time of borrow
<anon>:21         let handle = select.handle(nrx);
                               ^~~~~~
<anon>:21:36: 21:39 note: but, the lifetime must also be contained by the expression at 21:35...
<anon>:21         let handle = select.handle(nrx);
                                             ^~~
<anon>:21:36: 21:39 note: ...so that automatically reference is valid at the time of borrow
<anon>:21         let handle = select.handle(nrx);
                                             ^~~
error: aborting due to previous error
playpen: application terminated with error code 101

和 play.rust-lang 链接:http://is.gd/N1cF42 .

更改代码以在每个调用 try_recv 的代码中使用 Vec 和 iter，因为开发人员告诉我 select 还没有为此做好准备(还没有？)，但想知道哪些是其他解决方案或开发人员如何处理它。

Answer 1

找到这个库 https://github.com/mahkoh/comm它有许多 channel 实现，也可以(安全地)选择编译时未知的 channel 。来自文档:

use std::thread::{Thread};
use std::old_io::{timer};
use std::time::duration::{Duration};
use comm::{spsc};
use comm::select::{Select, Selectable};

let mut channels = vec!();
for i in 0..10 {
    let (send, recv) = spsc::one_space::new();
    channels.push(recv);
    Thread::spawn(move || {
        timer::sleep(Duration::milliseconds(100));
        send.send(i).ok();
    });
}
let select = Select::new();
for recv in &channels {
    select.add(recv);
}
let first_ready = select.wait(&mut [0])[0];
for recv in &channels {
    if first_ready == recv.id() {
        println!("First ready: {}", recv.recv_sync().unwrap());
        return;
    }
}