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Let's look at Rust's homepage: - Zero-cost abstractions - C++, in my opinion, is the founding father of zero-cost abstractions. - Move semantics - we've had thi

• 46Bit 10y ago
  For an experienced C++ dev it might not seem sensible. I can appreciate your viewpoint here. But it can become a hot place for higher-level people to do lower-level things and rapidly learn a lot, as it has for me and some other Rubyists.
• jdormit 10y ago
  > - Threads without data races - C++11 introduced a threading library as part of the language. We can avoid a lot of data races, deadlocks, etc. if you actually look deeper into how to implement the modern threading library well. So - we can implement threads without data races if we implement threads without data races? The reason people cite memory safety as a feature of Rust over C++ is because you get it for free, without having to do any additional work to achieve it.
  • soulbadguy 10y ago
    > The reason people cite memory safety as a feature of Rust over C++ is because you get it for free Nothing is free, language design is an exercise in compromise. OP might need to calm down a bit with the aggressive language, but underneath all that there is real message from people using (trying to ?) use modern C++ : The added safety you mentioned can 1) be really well approximated using modern C++ technics, 2) addressed by really well engrained coding standard and practice learned and known for a long time and doesn't apply for the in the unsafe part of rust that some of the libraries have to use. But i doesnt come at the cost of reduce expressiveness in the safe part of language, slower compiler time and high learning curve.
    • deleted 10y ago
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• Rusky 10y ago
  > - Move semantics - we've had this since C++11. C++11 move semantics and Rust move semantics are not equivalent. C++ requires every movable type to have a null state, and a (perhaps derived) move constructor that can potentially throw exceptions. Rust avoids the null state problem by statically omitting the constructor call (or, in the dynamic case, inserting a flag into the stack frame rather than forcing the programmer to reuse the object itself). It gains some ability to optimize by forbidding unwinding during a move. > I don't think you're gonna convince C++ (and C developers, of course) programmers who've been doing systems programming for a long time to stop everything and jump to Rust. That's not the goal. The goal is to provide a tool for new projects like Servo, or incremental partial rewrites like Firefox, or new infrastructure like ripgrep.
  • soulbadguy 10y ago
    > C++11 move semantics and Rust move semantics are not equivalent. C++ requires every movable type to have a null state, and a (perhaps derived) move constructor that can potentially throw exceptions. This doesn't sounds true to me. Can you clarify what you mean by moveable type have to have null state ? > Rust avoids the null state problem by statically omitting the constructor call You seems to be conflating move semantics and move optimization...
    • dbaupp 10y ago
      The parent correct: C++ runs destructors on all local variables, even if they have been "moved from", so it must be valid to do so. This translates into a null/"valid invalid"/sentinel state that the destructor can check to avoid truly destroying the underlying resource (which could result in double-freeing memory, or double-closing a file, or some other undefined behaviour). For instance, moving out of a unique_ptr will swap in NULL, and the destructor checks for that. Static omission of destructors in Rust is more than just an optimisation: locals (and other values) never have their destructors run once they've been moved-from, and thus no values need null states, and moving a value doesn't have to run arbitrary code (it can be, and is, just a memcpy).
    • Rusky 10y ago
• bogomipz 10y ago
  Thanks for the detailed explanation. I appreciate it.