Re: [boost] variant2 never empty guarantees (was: Re: Outcome/expected/etc/etc/etc)

Subject: Re: [boost] variant2 never empty guarantees (was: Re: Outcome/expected/etc/etc/etc)
From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2017-06-06 13:38:00

On Tue, Jun 6, 2017 at 5:29 AM, Andrzej Krzemienski via Boost
<boost_at_[hidden]> wrote:

>
> You are basically saying: provide the implementation that gives me strong
> guarantee when I meet condition X. ("X" being up to one type with
> potentially throwing move constructor).
>
> Your expectation is reasonable, but (I think) it is incompatible with other
> peoples' expectation: provide implementation that gives me never-empty
> guarantee when I meet condition Y. ("Y" in that case means I have a type
> with nothrow default constructor.)
>
> I do not think both expectations can be satisfied in one implementation.
>
> Regards,
> &rzej;
>

Agreed.  But I don't see much value in the never-empty guarantee if it
doesn't give you the strong guarantee.

Tony