Variadic functions (varargs)

[mahkoh]

Some food for thought:

fn f(args: ..i32) {
    // args has an anonymous type which implements Iterator<Item=i32>
    for arg in args {
        println!("{}", arg);
    }
}

fn g(args: ..&Any) {
    // args implements Iterator<Item=&Any>
    for (i, arg) in args.enumerate() {
        if arg.is::<&str> {
            println!("{}: &str: {}", i, arg.downcast_ref::<&str>().unwrap());
        } else if arg.is::<&i32> {
            println!("{}: i32: {}", i, arg.downcast_ref::<i32>().unwrap());
        }
    }
}

fn main() {
    f(1, 2, 3, 4);
    // 1
    // 2
    // 3
    // 4

    g(&"hello", &"world", &1, &2);
    // 0: &str: hello
    // 1: &str: world
    // 2: i32: 1
    // 3: i32: 2

    // Splice syntax
    let vec = vec!(1, 2, 3, 4);
    f(..vec.into_iter());
    // 1
    // 2
    // 3
    // 4
}

[glaebhoerl]

(See also #376.)

[mbrubeck]

See also #2137.

[cramertj]

Closing since I think #2137 covers this.