Rust 0.12.0 released

Re:Rust 0.12.0 released by steveklabnik on Thursday October 09, 2014 @01:30PM (#8433836)

Part of Rust's ownership system are 'lifetimes.' Without getting into the details, they're an annotation you occasionally add to code in certain situations. Like these two:

    fn get_mut<'a>(&'a mut self) -> &'a mut T;
    fn print<'a>(s: &'a str);

The 'a parts are the lifetime annotations.

We used to have a single inference rule for when you didn't need to write the annotation. With RFC 39[1], we added two more. These two extra inference rules removed 87% of the existing annotations, giving you this instead:

    fn get_mut(&mut self) -> &mut T;
    fn print(s: &str);

This is a pretty huge readability win.

1: https://github.com/rust-lang/rfcs/blob/master/active/0039-li...

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Re:Rust 0.12.0 released by untothebreach on Thursday October 09, 2014 @01:32PM (#8433860)

oh ok, thanks. i knew what lifetimes were, but was confused by the 'elision.' Apparently I didn't connect 'elision' with 'elide.' So, new vocab word for today :)

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Re:Rust 0.12.0 released by haberman on Thursday October 09, 2014 @05:05PM (#8435019)

What kind of cases do you still need to write explicit lifetimes?

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Re:Rust 0.12.0 released by steveklabnik on Thursday October 09, 2014 @05:30PM (#8435106)

I actually haven't had to since elision was implemented, so I can't give you a good rule of thumb from experience. Here's an overview of how the rules applied to the standard library at the time they were implemented, which is where the percentage came from: https://gist.github.com/aturon/da49a6d00099fdb0e861

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Re:Rust 0.12.0 released by xKingfisher on Thursday October 09, 2014 @11:52PM (#8436182)

The most common case I have run into is storing a reference inside another data structure.

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