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While other communities are already taking direct steps towards safety, the C++ community is still trying to define what safety means. I think it's funny and sa

While other communities are already taking direct steps towards safety, the C++ community is still trying to define what safety means. I think it's funny and sad at the same time! I didn't read the article (just browse it) but here's the TLDR from the article itself: ``` tl;dr: I don’t want C++ to limit what I can express efficiently. I just want C++ to let me enforce our already-well-known safety rules and best practices by default, and make me opt out explicitly if that’s what I want. Then I can still use fully modern C++… just nicer. ``` As is normal in C++, the defaults are wrong. Developers should "opt in" for unsafe instead of "opt out" of it!

soulbadguy 3y ago
> Developers should "opt in" for unsafe instead of "opt out" of it! Why ? C++ guiding principle is zero cost abstractions.
- estebank 3y ago
  It's "zero cost abstractions over what you would write by hand". If you argue that anyone doing array access should be doing bounds checks when in doubt, a C++ compiler performing bounds checks would still be considered zero(additional)-cost.
  - pptr 3y ago
    Well, when you are not in doubt you don't want unnecessary bounds checks.
    - estebank 3y ago
      If you can communicate to a human that a bounds check isn't necessary, you can communicate it to a compiler.
      - pptr 3y ago
        I'm all for better tools to help the compiler figure things out. Here is an example where I can't communicate the invariants to the compiler: ``` std::vector<int> v; ... v.push_back(2); std::sort(v.begin(), v.end()); // no need to check i < size because we know we will find value 2 somewhere in the v. for (int i = 0; i < v.size(); ++i) { if (v[i] == 2) return i; } ``` Note that in C++ you can manually mark code after the loop as unreachable, which would indeed skip the size check. But that's as bad as not checking bounds in the first place.
      - soulbadguy 3y ago
        No...
spacechild1 3y ago
> As is normal in C++, the defaults are wrong. Developers should "opt in" for unsafe instead of "opt out" of it! Isn't this exactly what he is saying?

soulbadguy 3y ago

> Developers should "opt in" for unsafe instead of "opt out" of it! Why ? C++ guiding principle is zero cost abstractions.

estebank 3y ago
It's "zero cost abstractions over what you would write by hand". If you argue that anyone doing array access should be doing bounds checks when in doubt, a C++ compiler performing bounds checks would still be considered zero(additional)-cost.
- pptr 3y ago
  Well, when you are not in doubt you don't want unnecessary bounds checks.
  - estebank 3y ago
    If you can communicate to a human that a bounds check isn't necessary, you can communicate it to a compiler.
    - pptr 3y ago
      I'm all for better tools to help the compiler figure things out. Here is an example where I can't communicate the invariants to the compiler: ``` std::vector<int> v; ... v.push_back(2); std::sort(v.begin(), v.end()); // no need to check i < size because we know we will find value 2 somewhere in the v. for (int i = 0; i < v.size(); ++i) { if (v[i] == 2) return i; } ``` Note that in C++ you can manually mark code after the loop as unreachable, which would indeed skip the size check. But that's as bad as not checking bounds in the first place.
    - soulbadguy 3y ago
      No...

spacechild1 3y ago

> As is normal in C++, the defaults are wrong. Developers should "opt in" for unsafe instead of "opt out" of it! Isn't this exactly what he is saying?