Add documentation example that doesn't involve unwrap about rust-url HOT 5 CLOSED

What does "raise an error" mean? Is it a compile-time error or run-time error? "url does not live long enough" sounds like a compile-time error, but that code builds fine for me. Is this the same code that the one that triggers the errors?

I can get this error message with code like this:

extern crate url;
use url::Url;

fn main(){
    let raw_url = "";
    let url_r = Url::parse(raw_url);
    let domain = match url_r {
        Ok(url) => {
            match url.domain() {
                Some(d) => d,
                None => return
            }
        }
        Err(e) => {
            println!("{}", e);
            return
        }
    };
    println!("{}", domain)
}

domain() returns a Option<&'a str> with a string slice that points to existing memory. That memory has to be kept around somewhere (such as a local variable) at least as long as the result of domain() exists. Here, the url_r variable (of type Result<Url, url::ParseError>) owns its contents, but it is moved out of in the Ok(url) pattern, which makes a url variable of type Url that owns its contents. url only exists in that match branch, so the result of domain() can only be used there. If you change the pattern to Ok(ref url), the url variable will be a reference &Url to the content of the url_r variable, and therefore the result of domain() will have a longer life time: that of url_r.

from rust-url.

You are right, I meant a compile time error.

I'm still a little confused about what I need to do to get this to work - which almost certainly has to do with my inexperience with Rust. Still though, it'd be nice if the documentation had examples of how best to work with URL's in this library, without panicking if something bad gets parsed.

from rust-url.

I should note I tried changing the line to Ok(ref url) and I'm still getting an error - a slightly different error.

error: `(url_r:core::result::Ok).0` does not live long enough

from rust-url.

The code you copied in the first message compiles fine for me, so I suspect that the code trigger an error for you is not the same. Please provide the actual code that triggers the error so that I can reproduce it. (Preferably, a minimal form of it.)

from rust-url.

Hmm, you're right, it turns out it had to do with another part of my program - sorry :(

from rust-url.