username() -> Option<&str>?

[ConnyOnny]

Hey, just wondering why username() returns an empty string and password() returns None if not set.
This makes my code a little weird:

let mut username = parsed_url.username();
if username.is_empty() {
    username = "anonymous";
}
let password = parsed_url.password().unwrap_or("anonymous");

If there isn't a good reason for this, I'd like to propose that username() should also return an Option.

[SimonSapin]

This reflects the data model in the spec:

https://url.spec.whatwg.org/#urls

A URL’s username is an ASCII string identifying a user. It is initially the empty string.

A URL’s password is either null or an ASCII string identifying a user’s credentials. It is initially null.

To be honest I don’t know the reason for this difference. @annevk, can you say more? If the username could also be null, I suppose it would be null in http://example.com/ but still the empty string in http://example.com@/.

[ConnyOnny]

Some experiments:

"http://x.com"
username: ""
password: None

"http://@x.com"
username: ""
password: None

"http://:@x.com"
username: ""
password: Some("")

"http://example.com@/"
thread 'main' panicked at 'invalid url: EmptyHost'

This makes it impossible to specify the empty string as a username, as the application will always think, there was no username given at all.

[annevk]

You can differentiate between password being present and not, but not with username.

[SimonSapin]

@annevk yes, in the model as currently specified in https://url.spec.whatwg.org/#urls. But is there a specific reason it is specified that way?

[annevk]

As far as I know that matches user agents and how the syntax works.

[SimonSapin]

In fact the standard went in the opposite direction: removing the distinction between no password and an empty password whatwg/url#186

[blanham]

@SimonSapin Would that indicate then that password should also not be Option<&str>? Also, would you be open to a PR that adds a convenience function getter for username (and perhaps password, if it is changed to match the standard) that returns an Option<&str>? Then you could do this, as @ConnyOnny was proposing:

let username = parsed_url.username_as_option().unwrap_or("anonymous");
let password = parsed_url.password_as_option().unwrap_or("anonymous");

With the current focus on ergonomics in the community I think it would be a nice addition.