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Box totally implements Send: https://doc.rust-lang.org/std/boxed/struct.Box.html#synthetic-implementations https://doc.rust-lang.org/std/boxed/struct.Box.html#s
by Rusky 8y ago
Box totally implements Send: https://doc.rust-lang.org/std/boxed/struct.Box.html#synthetic-implementations https://doc.rust-lang.org/std/boxed/struct.Box.html#syntheti...
Also I'm not sure how ? obscures control flow to the same level as C++, which propagates exceptions with no syntactic marker at all.
- brian-armstrong 8y agoWell to be fair, I would never advocate using exceptions. Also I’m quite sure Box doesn’t. I’ve seen compiler errors when attempting to pass one via mpsc.
- steveklabnik 8y agoYour parent’s link says Box implements Send only when it’s T is Send, which makes sense.
- brian-armstrong 8y agoI guess? If you’re transferring ownership of something to another thread, that’s perfectly safe. Needing to implement (??) Send for a struct or pod type is cumbersome when it’s something you’d do pretty often.
- Rusky 8y agoGood thing Send is implemented automatically for types based on their contents, then. If you're trying to send a value to another thread, Rust will only stop you if the author of some type somewhere inside it has opted out, and none of its containers ever opted back in (as Box does).
- GolDDranks 8y agoYou don't need to implement Send for POD types – it is automatically implemented. Almost all types implement Send. There are only a few exceptions that I know of: Rc (the non-atomic reference counted pointer) doesn't implement Send because it doesn't support atomically updating the count. Also raw pointers don't implement Send.
- brian-armstrong 8y agoThe fact that we’re even having this conversation, caused by compiler error ambiguity, demonstrates my point about ergonomics nicely :)
- steveklabnik 8y agoPlease file bugs if the errors are confusing!
- brian-armstrong 8y agoEh, they’re probably fine for regular users. They are just nonsensical when you’re starting out.
- steveklabnik 8y agoWe care just as much for people just starting out as we do for regular users; possibly even more!
- huhlig 8y agoIf you want compiler ambiguity in C++ look no further than Templates... C++ is rarely ergonomic to use.
- psyclobe 8y agoI like templates, because to date there is not a popular language that can do compile time stuff it can do. And no joke, some of the stuff you can do is quite amazing.
- chi3 8y agoWell, there's plenty to say about C++ compiler errors too!
- brian-armstrong 8y ago
- Jweb_Guru 8y agoIt's something you should almost never need to do and about half the manual implementations I see of Send are wrong. Trust Rust on this one.
- sacado2 8y agoI preferred the "try!" syntax. The ? is harder to parse visually, harder to find, and makes the language a little more complex (that's one more operator, one more thing to understand, one more thing to parse for tools, etc.)