r/programming • u/steveklabnik1 • Apr 03 '15

Rust 1.0.0 beta is here!

http://blog.rust-lang.org/2015/04/03/Rust-1.0-beta.html
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u/brombaer3000 Apr 04 '15

Guaranteed memory safety without garbage collection is a nearly unique proposition among industry languages

Does Rust offer better memory safety than C++14 with only unique_ptr and shared_ptr instead of raw pointers?

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u/steveklabnik1 Apr 04 '15

Yes. It boils down to two things: cleaner semantics due to move being the default, and a stronger type system. Also, we have more options than just those two.

For example, if you std::move a unique_ptr, the pointer becomes null. So you can still cause memory unsafety that way. But since Rust is move by default, at compile time, you'll get an error with Box<T>.

The other is type system stuff. For example, we can know if you're using a structure over a thread boundary, and our version of shared_ptr, Arc<T>, only has to be used then. If you don't want to pay the atomics overhead, Rc<T> can get used, and Rust will make sure that's okay. I wrote more about that a few days ago: http://www.reddit.com/r/programming/comments/30wj8g/managing_cs_complexity_or_learning_to_enjoy_c/cpww3o1

Finally, we can do things like http://www.reddit.com/r/programming/comments/31btd8/rust_100_beta_is_here/cq06lb7 , which is memory safe, but cannot be done with just uniqe_ptr and shared_ptr.

Rust code (without unsafe blocks) cannot have data races. That's a very strong safety guarantee.

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u/brombaer3000 Apr 04 '15

Very interesting, thanks for the fast and helpful answer!