Option.as_ref() possible example mistake?

[remdragon]

url: https://doc.rust-lang.org/nightly/core/option/enum.Option.html

function: as_ref()

Examples:

Converts an Option<String> into an Option<usize>, preserving the original.

Perhaps I'm just confused, but shouldn't that say:

Converts an Option<String> into an Option<&str>, preserving the original.

[ehuss]

Transferring to the rust-lang/rust repository, as that is where the standard library documentation is.

I think it is trying to illustrate the conversion from Option<String> → Option<&String> → Option<usize>. The text is just eliding the middle step, and explaining where it is starting from and where it is finishing.

[aristotaloss]

No, that seems fine; what confuses you (or leads you to the &str conclusion)? I could follow Option<&String> but not Option<&str>. Perhaps you're thinking the Deref<Target=str> impl on String would make the Option contain Option<&str> or such?

[remdragon]

I guess I'm extremely confused then. If I have an &Option<String>, what good does an Option<usize> do me? If I have &Some( "fubar" ), how does that translate to a usize? Is it giving me the length of the string or it's pointer in memory? Neither seems useful nor relevant to the description of "Converts from &Option to Option<&T>.".

[zirconium-n]

I guess I'm extremely confused then. If I have an &Option, what good does an Option do me?

You can call Option::map.

If I have &Some( "fubar" ), how does that translate to a usize? Is it giving me the length of the string or it's pointer in memory? Neither seems useful nor relevant to the description of "Converts from &Option to Option<&T>.".

Converts an Option<String> into an Option<usize>, preserving the original just describes the example code's functionality, not Option::as_ref's. It's showing one of the ways you could use Option::as_ref.

[remdragon]

Okay, sorry, I understand now that comment is talking about the upcoming example instead of discussing as_ref() in general. In order to help others not experience the same confusion I did, perhaps I could suggest a tweak to the wording, such as: Calculates the length of an Option<String> as an Option<usize> without consuming the original String.?

[M1ngXU]

length

memory address

[zacklukem]

@rustbot claim