Re: [boost] [outcome v2] Please comment on new result<T, EC> reference API docs

Subject: Re: [boost] [outcome v2] Please comment on new result<T, EC> reference API docs
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2017-06-22 00:09:46

On Wed, Jun 21, 2017 at 4:58 PM, Niall Douglas via Boost <
boost_at_[hidden]> wrote:

> On 22/06/2017 00:21, Peter Dimov via Boost wrote:
> >>>> https://dedi4.nedprod.com/static/result-v2/doc_result.html
> >
> > 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.
>

Wasn't this one of the issues people took with Noexcept, that since it
works with any return type whatsoever, there is no clear invariant, and you
could end up in a situation where you have a value and an error? (I
actually agree with this criticism, but in my mind this is a small price to
pay for not burdening return objects with transporting errors as well as
values.)