On 22/06/2017 00:21, Peter Dimov via Boost wrote:
Niall, what does result<R, void> represent?
Same as expected<R, void>. It's legal to return that failure occurred, but no information as to why. I see that as being possibly useful. What's far more interesting is result<void, void>. Yes expected<void, void> is also legal too. Where things get mind bendy is that v2 result<T, E> can return a T with additional info E, so you can quite legitimately have a result<void, void> with both .has_value() and .has_error() returning true. I agree before you say it that that is daft. But I see no good reason to not support it other than "that is daft". And besides, outcome<void, void, exception_ptr> looks much more useful, and that would have a result<void, void> internally, so there is a real actual use case for result<void, void>. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/