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611 points LorenDB | 2 comments | | HN request time: 0s | 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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jchw ◴[] No.43908844[source]
Google has been doing a very similar, but definitely somewhat uglier, thing with StatusOr<...> and Status (as seen in absl and protobuf) for quite some time.

A long time ago, there was talk about a similar concept for C++ based on exception objects in a more "standard" way that could feasibly be added to the standard library, the expected<T> class. And... in C++23, std::expected does exist[1], and you don't need to use exception objects or anything awkward like that, it can work with arbitrary error types just like Result. Unfortunately, it's so horrifically late to the party that I'm not sure if C++23 will make it to critical adoption quickly enough for any major C++ library to actually adopt it, unless C++ has another massive resurgence like it did after C++11. That said, if you're writing C++ code and you want a "standard" mechanism like the Result type, it's probably the closest thing there will ever be.

[1]: https://en.cppreference.com/w/cpp/utility/expected

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loeg ◴[] No.43910401[source]
Facebook's Folly has a similar type: folly::Expected (dating to 2016).
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1. throwaway2037 ◴[] No.43912122[source]
If I had to guess, that idea came from Andrei Alexandrescu.
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2. loeg ◴[] No.43912445[source]
Bingo.

https://github.com/facebook/folly/commit/4d932ecc53c7a722671...