Four Years of Rust • Hacker News Board

Re: Four Years of Rust

#201

Post by kevinmgranger » Wed, May 22, 2019, 3:57 PM UTC

manwe150 wrote: post #160

dpc_pw wrote: post #132

Earlier quoted context omitted.

> Many GC enabled system languages do offer both mechanisms. ? Can you give me an example? Java's `finalize` is not deterministic destruction. D's scope guards (or Go's `defer`) are also not like destructors, because a calling code has to take care of them. > It is a matter of enjoying productivity it offers, There's hardly any productivity gain, and it is being offset by productivity gained by a reliable and hassle-…

Not exactly a systems language, but Python has deterministic destruction (due to the use of reference counting) of non-cyclic data structures. Edit: Oh, and if you don’t think that’s enough, note that Rust doesn’t guarantee destruction to ever occur in that case (“considered safe”): https://doc.rust-lang.org/book/ch15-06-reference-cycles.html

> Python has deterministic destruction

Not quite.

https://docs.python.org/3/reference/datamodel.html#object.__...

> It is not guaranteed that __del__() methods are called for objects that still exist when the interpreter exits.

Re: Four Years of Rust

#202

Post by thenewwazoo » Fri, May 24, 2019, 2:28 AM UTC

Outpox wrote: post #62

thenewwazoo wrote: post #43

Earlier quoted context omitted.

It's funny, I give almost the exact opposite advice when I'm helping Rust newbies. My diktat is "clone is banned unless you can explain why you must have it", and then I teach people about what a move is and how to think about lifetimes. w.r.t. Arc/Rc, I'd say that it might feel verbose at first, but it makes explicit what a GC does implicitly, and you can get all the benefits of Rust's ownership model at the same ti…

Have you written about this (your diktat about clone()) somewhere? I'd be interested to read more.

FYI, I posted it at https://thenewwazoo.github.io/clone.html

Re: Four Years of Rust

#203

Post by wyatwerp » Fri, May 24, 2019, 7:10 PM UTC

dpc_pw wrote: post #159

wyatwerp wrote: post #153

Earlier quoted context omitted.

I truly was curious about your C/C++ code - good for you that it was less C++ and more C! I don't know any masochists, so I don't know anybody who likes to work in C++ (even with just composition and generics), or even any reluctant "expert". I get away from segfaults because I am on server & can get away by more static copying of data (it pales in comparision to what alternatives offer). I can see why you think Rust…

> AutoSAR, was it? Just a real-time hypervisor for Tegra underlying Nvidia Automotive platform. MISRA C, ISO 26262. Bleh. :D > so the cognitive load of designing at that scale with borrow-checking seems prohibitive I have multiple 1k - 10k line Rust projects on github, and I hardly ever deal or think about lifetimes. I just randomly opened a project of mine on github, opening some major files and there's literally 0…

MISRA C? Cool!

About the design model for programming in Rust, I guess only making the time to try writing something in Rust can answer the question. It is interesting how the steepness of the Rust learning curve could actually be a hook to get people to try it, which is all any well-designed language would need to gain adherents.

Back to critical systems programming, does MISRA C have a "certified" compiler like CompCert C or something? If so, Rust usage in such a niche must be a long way away - even if one could "certify" the Rust compiler code, how would one "certify" the million+ lines of C++ in LLVM!