expected VS outcome

On this topic Sy Brand is a guarantee, in fact he did the https://github.com/TartanLlama/expected and several presentation of the subject.

In the meantime, I may use the TartanLlama implementation (here) and plan around replacing it with the real deal in the near future.

Sy Brand's tl::expected

expected is my favourite little part of cpp23, I’m using it often in codebase with https://github.com/TartanLlama/expected 😁

outcome and/or expected

Eventually you'll be able to use std::expected in C++23!

https://en.cppreference.com/w/cpp/header/expected

Don't throw exceptions, require the caller to handle errors and propagate them up the stack (everything returns an expected) if they cannot be handled. You are forced to model the error domains instead of just throwing an exception and assuming the caller knows to catch it and do something with it.

Java has checked exceptions, but, Kotlin decided to abandon them.

The nice codebases I have worked on stick to the Result type in Swift or Kotlin. And thus you are forced to 'translate' errors (exceptions?) as described in Alan Griffith's 'Exceptional Java'.

https://accu.org/journals/overload/10/48/griffiths_406/

"If a checked exception is thrown (to indicate an operation failure) by a method in one package it is not to be propagated by a calling method in a second package. Instead the exception is caught and "translated". Translation converts the exception into: an appropriate return status for the method, a checked exception appropriate to the calling package or an unchecked exception recognised by the system. (Translation to another exception type frequently involves "wrapping".)"

If you can't wait for C++23, there's a single header implementation here.

https://github.com/TartanLlama/expected

https://github.com/ned14/outcome/tree/develop/abi-compliance uses both in a CI pass to ensure Outcome never changes anything which breaks either API or ABI with earlier versions.

outcome and/or expected

A "Sample Usage" appears on the front page of the docs: https://ned14.github.io/outcome/

I recently came across boost outcome as I was searching for a better error handling method. It took me a minute to get a hang of it but now I love it. After creating my own policy and a few aliases for easier use.

std::optional and std::variant can be a bit awkward to use in this scenario, though. Consider a dedicated type like boost::outcome (standalone versions) or one of the implementations of the proposed std::expected.

Minimum possible compile time impact is a key goal of https://github.com/ned14/outcome. We ship a single header edition which only includes the low impact standard headers as listed at https://github.com/ned14/stl-header-heft. We also don't use union storage for non-TC non-MB types in order to avoid complex metaprogramming execution by the compiler per instantiation.

It's really weird that I wrote the above, and then this bug was reported to Outcome: https://github.com/ned14/outcome/issues/244. Here is my exact complaint about lack of lifetime tracking in C++.