[klauserc]

Yes! One of the worst bugs to debug in my entire career boiled down to a piece of Java mutating a HashSet that it received from another component. That other component had independently made the decision to cache these HashSet instances. Boom! Spooky failure scenarios where requests only start to fail if you previously made an unrelated request that happened to mutate the cached object.

This is an example where ownership semantics would have prevented that bug. (references to the cached HashSets could have only been handed out as shared/immutable references; the mutation of the cached HashSet could not have happened).

The ownership model is about much more than just memory safety. This is why I tell people: spending a weekend to learn rust will make you a better programmer in any language (because you will start thinking about proper ownership even in GC-ed languages).

[arresin]

A weekend?

[IshKebab]

Yeah that's definitely optimistic. More like 1-6 months depending on how intensively you learn. It's still worth it though. It easily takes as long to learn C++ and nobody talks about how that is too much.

[AquilaFasciata]

Yes. I learned Rust in a weekend. Basic Rust isn't that complicated, especially when you listen to the compiler's error messages (which are 42x as helpful compared with C++ compiler errors).

[arresin]

Damn. You are a smart person. It’s taken me months and I’m still not confident. But I was coming from interpreted languages (+ small experience with c).

[brabel]

> This is an example where ownership semantics would have prevented that bug.

It’s also a bug prevented by basic good practices in Java. You can’t cache copies of mutable data and you can’t mutate shared data. Yes it’s a shame that Java won’t help you do that but I honestly never see mistakes like this except in code review for very junior developers.

[zozbot234]

The whole point is that languages like Java won't keep track of what's "shared" or "mutable" for you. And no, it doesn't just trip up "very junior developers in code review", quite the opposite. It typically comes up as surprising cross-module interactions in evolving code bases, that no "code review" process can feasibly catch.

[brabel]

Speak for yourself. I haven't seen any bug like this in Java for years. You think you know better and my experience is not valid? Ha. Ok. Keep living in your dreams.

[IshKebab]

Yes I think he knows better and your experience is not valid.

Well, maybe not valid, but insufficient at least.