Re: [boost] [outcome] Exception safety guarantees

Subject: Re: [boost] [outcome] Exception safety guarantees
From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2017-05-30 21:45:28

2017-05-30 17:43 GMT+02:00 Howard Hinnant via Boost <boost_at_[hidden]>:

> On May 30, 2017, at 11:30 AM, Andrzej Krzemienski via Boost <
> boost_at_[hidden]> wrote:
> >
> > std::sort, apart from what it is
> > allowed to do, is also require to produce the output range that is the
> > permutation of the input range. Assuming no moved-from states on input,
> if
> > for some reason it starts to put objects in a moved-from state and then
> > using this value for sorting further, even if moved-from state is
> > well-ordered, you will get this moved from state in the output range, but
> > it was not in the input range.
>
> Theoretically, a std::sort algorithm could move from x[i], then
> subsequently perform x[i] < x[i], act on the return of false, and then move
> assign a new value into x[i], and still get the right answer.  I know of no
> shipping std::sort that actually does this.
>

Yes, it could do it :)
I guess the only purpose would be to verify if the moved-from state is well
ordered with other values.

Regards,
&rzej;