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They all optional. Don't throw exceptions and they won't unwind. Standard library is optional, there're good alternatives like ATL and EASTL. Microsoft's packag

They all optional. Don't throw exceptions and they won't unwind. Standard library is optional, there're good alternatives like ATL and EASTL. Microsoft's package is optional, change a compiler switch and your binary will stop using or requiring that package. However, manual memory management makes development more expensive. Especially if you don't crunch numbers but parse strings. C++ probably ain't a good replacement for Go. For the last decades people and whole industries have been migrating the other way, from C++ to higher level memory safe languages, initially Java and C# then others followed.

jchw 7y ago
Sigh. I avoided mentioning that the C++ runtime was optional because I was trying not to be pedantic and I assumed in context it would be understood that this was irrelevant. I think I should’ve just made my point earlier, but: - This all started with someone mentioning that C++ doesn’t have ‘bad runtime behavior’ because it doesn’t have a runtime, but this is false. It has a runtime, or to be exact, a specification for one, and I think it is safe to say a vast, perhaps extreme, majority of C++ developers are using it. - If you opt to not use the runtime, then your runtime behavior is dictated somewhere else, but runtime behaviors don’t go away. In freestanding, you may be your own runtime, but then your runtime behavior is defined by the machine you’re running on. You just get to choose what layer of abstraction you are sitting on. - edit: And also, as a point I forgot to mention initially, I don’t really feel like freestanding C++ vs standard Go is an apples-to-apples comparison. I think the point was that the C++ has less runtime behavior, since it doesn’t have a scheduler or garbage collector, but extrapolating that to no runtime is wrong even if the runtime is optional.
- Const-me 7y ago
  As far as I understood the context, it was about language runtimes. Underneath all languages, there’re usually OS kernel, drivers and hardware. They all have non-trivial amount of unexpected behavior, especially under load. But these apply to code written in all languages, almost equally. BTW, C++ does have a scheduler. Optional like the rest of the runtime, but it’s 1 line of code away in all modern compilers, that line starts with #pragma omp.
  - jchw 7y ago
    Yes, that seems about right. There’s always behavior at runtime, and your language shields it away from you to varying degrees. It is the same for all languages, which is exactly what I am trying to drive home. However, even if you go to the extreme of not using any features that require runtime support, if you are using hosted C++, in practice you still have one bit of runtime: the entrypoint. Technically, an operating system could implement the bits that call main, but to the best of my knowledge none of them ever have. So every compiled binary from every hosted C++ implementation begins at the runtime library. (Admittedly, normally the C runtime library, since C++ doesn’t differ here, but that is just another layer deep of pedantics. In practice, everyone has a runtime.) Nitpick: As far as I am aware OpenMP is not part of the language itself but an extension. But yeah, you could argue that is runtime scheduling in C++, I think.
    - saagarjha 7y ago
      If you don’t have static initalizers you should just be able to set your entrypoint to be main, no?
      - jchw 7y ago
        Not really, because the entrypoint of executables is OS dependent and may not resemble the “main” function signature. I actually don’t know what Linux dumps on the stack/registers before calling your entrypoint, though, to be honest.
        saagarjha 7y ago
        On a freestanding environment, the signature of main doesn't have to be the standard "int main(int argc, char argv)". Oh, and on Linux the the arguments to main are put on the stack, which you can see is handled by _start: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/start.S;h=ae08f98180e45f39402459747e462da8d94bb64d;hb=HEAD https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86...
- int_19h 7y ago
  This isn't about freestanding C++. There's very little in the C++ standard library that can cause exceptions. Off the top of my head, it's throwing new (which nobody relies on anyway because of Linux OOM behavior); stuff like vector::at() that you have to use explicitly; and iostreams that are so horrible in general that they're usually avoided altogether.
  - murderfs 7y ago
    There are tons of things that throw exceptions in the standard library with no alternative. std::bad_alloc can get thrown from half the standard library (and it's a lot less implausible than new throwing, because of address space exhaustion on 32-bit). Any constructor that takes input that can be invalid has to throw (e.g. giving a malformed regex to std::regex). The really obnoxious ones are std::stoi, stol, etc. which were added in C++11 as a replacement for strtol and friends, but throw on overflow/invalid input instead of returning a result type or a bool with out parameter.

jchw 7y ago

Sigh. I avoided mentioning that the C++ runtime was optional because I was trying not to be pedantic and I assumed in context it would be understood that this was irrelevant. I think I should’ve just made my point earlier, but: - This all started with someone mentioning that C++ doesn’t have ‘bad runtime behavior’ because it doesn’t have a runtime, but this is false. It has a runtime, or to be exact, a specification for one, and I think it is safe to say a vast, perhaps extreme, majority of C++ developers are using it. - If you opt to not use the runtime, then your runtime behavior is dictated somewhere else, but runtime behaviors don’t go away. In freestanding, you may be your own runtime, but then your runtime behavior is defined by the machine you’re running on. You just get to choose what layer of abstraction you are sitting on. - edit: And also, as a point I forgot to mention initially, I don’t really feel like freestanding C++ vs standard Go is an apples-to-apples comparison. I think the point was that the C++ has less runtime behavior, since it doesn’t have a scheduler or garbage collector, but extrapolating that to no runtime is wrong even if the runtime is optional.

Const-me 7y ago
As far as I understood the context, it was about language runtimes. Underneath all languages, there’re usually OS kernel, drivers and hardware. They all have non-trivial amount of unexpected behavior, especially under load. But these apply to code written in all languages, almost equally. BTW, C++ does have a scheduler. Optional like the rest of the runtime, but it’s 1 line of code away in all modern compilers, that line starts with #pragma omp.
- jchw 7y ago
  Yes, that seems about right. There’s always behavior at runtime, and your language shields it away from you to varying degrees. It is the same for all languages, which is exactly what I am trying to drive home. However, even if you go to the extreme of not using any features that require runtime support, if you are using hosted C++, in practice you still have one bit of runtime: the entrypoint. Technically, an operating system could implement the bits that call main, but to the best of my knowledge none of them ever have. So every compiled binary from every hosted C++ implementation begins at the runtime library. (Admittedly, normally the C runtime library, since C++ doesn’t differ here, but that is just another layer deep of pedantics. In practice, everyone has a runtime.) Nitpick: As far as I am aware OpenMP is not part of the language itself but an extension. But yeah, you could argue that is runtime scheduling in C++, I think.
  - saagarjha 7y ago
    If you don’t have static initalizers you should just be able to set your entrypoint to be main, no?
    - jchw 7y ago
      Not really, because the entrypoint of executables is OS dependent and may not resemble the “main” function signature. I actually don’t know what Linux dumps on the stack/registers before calling your entrypoint, though, to be honest.
      - saagarjha 7y ago
        On a freestanding environment, the signature of main doesn't have to be the standard "int main(int argc, char argv)". Oh, and on Linux the the arguments to main are put on the stack, which you can see is handled by _start: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/start.S;h=ae08f98180e45f39402459747e462da8d94bb64d;hb=HEAD https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86...
int_19h 7y ago
This isn't about freestanding C++. There's very little in the C++ standard library that can cause exceptions. Off the top of my head, it's throwing new (which nobody relies on anyway because of Linux OOM behavior); stuff like vector::at() that you have to use explicitly; and iostreams that are so horrible in general that they're usually avoided altogether.
- murderfs 7y ago
  There are tons of things that throw exceptions in the standard library with no alternative. std::bad_alloc can get thrown from half the standard library (and it's a lot less implausible than new throwing, because of address space exhaustion on 32-bit). Any constructor that takes input that can be invalid has to throw (e.g. giving a malformed regex to std::regex). The really obnoxious ones are std::stoi, stol, etc. which were added in C++11 as a replacement for strtol and friends, but throw on overflow/invalid input instead of returning a result type or a bool with out parameter.