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611 points LorenDB | 2 comments | | HN request time: 0.428s | source
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dvratil ◴[] No.43908097[source]
The one thing that sold me on Rust (going from C++) was that there is a single way errors are propagated: the Result type. No need to bother with exceptions, functions returning bool, functions returning 0 on success, functions returning 0 on error, functions returning -1 on error, functions returning negative errno on error, functions taking optional pointer to bool to indicate error (optionally), functions taking reference to std::error_code to set an error (and having an overload with the same name that throws an exception on error if you forget to pass the std::error_code)...I understand there's 30 years of history, but it still is annoying, that even the standard library is not consistent (or striving for consistency).

Then you top it on with `?` shortcut and the functional interface of Result and suddenly error handling becomes fun and easy to deal with, rather than just "return false" with a "TODO: figure out error handling".

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jeroenhd ◴[] No.43908294[source]
The result type does make for some great API design, but SerenityOS shows that this same paradigm also works fine in C++. That includes something similar to the ? operator, though it's closer to a raw function call.

SerenityOS is the first functional OS (as in "boots on actual hardware and has a GUI") I've seen that dares question the 1970s int main() using modern C++ constructs instead, and the API is simply a lot better.

I can imagine someone writing a better standard library for C++ that works a whole lot like Rust's standard library does. Begone with the archaic integer types, make use of the power your language offers!

If we're comparing C++ and Rust, I think the ease of use of enum classes/structs is probably a bigger difference. You can get pretty close, but Rust avoids a lot of boilerplate that makes them quite usable, especially when combined with the match keyword.

I think c++, the language, is ready for the modern world. However, c++, the community, seems to be struck at least 20 years in the past.

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1. Rucadi ◴[] No.43909952[source]
I created a library "cpp-match" that tries to bring the "?" operator into C++, however it uses a gnu-specific feature (https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html), I did support msvc falling-back to using exceptions for the short-circuit mechanism.

However it seems like C++ wants to only provide this kind of pattern via monadic operations.

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2. tialaramex ◴[] No.43913492[source]
You can't really do Try (which is that operator's name in Rust) because C++ lacks a ControlFlow type which is how Try reflects the type's decision about whether to exit early.

You can imitate the beginner experience of the ? operator as magically handling trivial error cases by "just knowing" what should happen, but it's not the same thing as the current Try feature.

Barry Revzin has a proposal for some future C++ (lets say C++ 29) to introduce statement expressions, the syntax is very ugly even by C++ standards but it would semantically solve the problem you had.