Subject: Re: [boost] [variant2] Need rationale for never-empty guarantee
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2019-03-02 00:02:46
On Fri, Mar 1, 2019 at 2:18 PM Andrzej Krzemienski via Boost <
boost_at_[hidden]> wrote:
> variant2 also only provides *basic* exception safety guarantee: you can be
> assigning a variant containing type B to a variant containing type A and
> end up with variant containing type C. Here's an example:
> https://wandbox.org/permlink/AObFiUKgeXIEiXQa
>
> My point is, you can only observe the valueless state in variant if you
> work with objects that threw from a basic-guarantee operation. But if you
> do this, you already have mess in your program regardless if you are using
> variants or not.
This is true only if we define "mess" to mean "an unspecified but valid
state".