2017-06-20 0:42 GMT+02:00 Richard Hodges via Boost <boost@lists.boost.org>:
To somewhat challenge this statement, The following is an example of how I would use Boost.Outcome if I had it available at the time when I was solving this parsing problem: https://github.com/akrzemi1/__sandbox__/blob/master/outcome_ practical_example.md
In the above code, the return type of expected<std::vector<Distrib>, BadInput> is equivalent in all respects to 2-state variant.
Conceptually, yes.
If it were implemented as a boost/std::variant, then the two states could be handled with a static visitor - which would provide a compile-time guarantee that any future third state was not missed.
When I use `expected` I also get a guarantee that there will always be two types to handle - no more. What I also gain is the ability to use the TRY operation, which makes the program twice shorter, while not compromising clarity or type safety.
I don't think we're gaining anything with outcome, other than perhaps a label which serves to express intent?
Yes, it is mostly for: clarity of intent, terseness, static safety (invalid usages detected at compile-time). Regards, &rzej;