undefined | Better HN

0 pointscb3215y ago0 comments

This seems oriented around just code bases you have seen personally rather than fundamental C limitations and so misleads. To clarify: C can do template-like macros for type specialization (and this is common in some code bases) and easier to debug ways [1] { I've personally used a variant of [1] techniques since the mid 90s }. C can do setjmp & longjmp exceptions and you can even do a TRY/CATCH like exception macros. Function pointers are in stdlib interfaces (e.g. qsort) and generally pretty common in C code. I believe gcc has been able to inline through C function pointers ("de-virtualize", though you qualify with "really" there..) in the same translation unit for like 2 decades now with the right compiler flags/annotations.

It is true that C cannot do full template meta-programming or certain state save/restore optimizations faster than setjmp/longjmp. Hard/painful/trivial are all a bit more subjective and relative to exposure/practice/training/etc.

Personally, I think Nim [2] is a much friendlier way to go than either C++ or Python without the pitfalls of either, but the ecosystem is admittedly much smaller. Also, I've yet to hit something where re-writing the C++/Rust in Nim did not speed things up from "at least a little" to "quite a bit". { This is more an artifact of "performance incautious programming" in the C++/Rust. Too many people fall into the trap that, since a language has a reputation for speed, they don't need to think. This is probably largely why @mehrdadn's original article had the title it did. ;-) }

[1] https://github.com/glouw/ctl/

[2] https://nim-lang.org

0 comments

kllrnohj5y ago

> C can do template-like macros for type specialization

Of course, C++ has those some macro capabilities. But macros are quite limited, and typically the "template-like" ones rely on non-standard preprocessor support like typeof for swap. But then you still lack the ability to specialize swap for different types (eg, you can't replicate std::swap's behavior on std::vector in C)

> C can do setjmp & longjmp exceptions and you can even do a TRY/CATCH like exception macros.

You can, but that's now another parameter to pass along down the call stack, and as LLVM notes https://llvm.org/docs/ExceptionHandling.html#setjmp-longjmp-... it still negatively impacts the non-exception performance path.

cb321OP5y ago

While C macros are limited, you underestimate their range. You can absolutely create specialized swaps without typeof (not part of the C preprocessor, incidentally), and the CTL which I linked to even has one. You just tell the macro the name of the type. And you can just invoke swap_ref or something if you want a more indirect one. There's no overloading. So, yeah, you need to know what you are operating upon, or abstract qualities thereof.

Sure, the use of these things in C is (usually) a bit more verbose/burdensome than C++. The misleading statements were performance-oriented, not syntactic sugar-oriented, and I already granted exception optimization. (Some folks, like Go/Rust authors, would tell you exceptions are bad anyway.)

j / k navigate · click thread line to collapse