Convenient method for match and parsing values implementing FromStr

[kaoet]

I wish I could match a string and parse the captured groups in a single call. I imagine the new method return a Result<tuple, SomeError>, where each type inside that tuple is having FromStr implemented.

let log_line = "Time: 2014-11-28T12:45:59.324310806Z IP: 192.168.3.4 User: kaoet";
let re = Regex::new(r"Time: (.+?) IP: (.+?) User: (.+)");
let (time, ip, user) : (DateTime<Utc>, IpAddr, String) = re.match_and_parse(log_line).unwrap();

I know one of the problem here is the choice of SomeError, since different FromStr have different Err type. Maybe Box<dyn Error + 'lifetime_of_the_str> is a viable solution.

[BurntSushi]

It's not really clear to me how this machinery is supposed to work. What enables FromStr to work on tuples, for example? The error situation also looks pretty unfortunate. And what happens when there isn't a match? On top of that, I don't think this actually saves much work, and thus isn't buying that much convenience. I'd encourage you to write out the alternative and compare them.

Finally, this would also have the same issues as #824. Your API doesn't account for captures that don't participate in a match.