Re: [boost] [optional] Why was optional<T>::reset() deprecated?

Subject: Re: [boost] [optional] Why was optional<T>::reset() deprecated?
From: Beman Dawes (bdawes_at_[hidden])
Date: 2016-03-02 06:21:05

On Wed, Mar 2, 2016 at 3:20 AM, Andrey Semashev <andrey.semashev_at_[hidden]>
wrote:

> On 2016-03-02 01:51, Andrzej Krzemienski wrote:
>
>> At some earlier stages of development, boost::optional did not have the
>> assignment from boost::none_t (and probably also from T); and reset was
>> the
>> only way to efficiently change the optional from the state of having the
>> value to the state of not having the value.
>>
>> After the addition of more fancy syntax (conversion to bool, assignment
>> from none_t), reset() (and is_initialized()) became redundant, and hence
>> the deprecation.
>>
>> I got that from reading Boost mailing archives once.
>>
>
> FWIW, I don't think that having support for 'none' is enough reason to
> deprecate 'reset' (same for 'is_initialized'). I know some of my colleagues
> who prefer these methods to the fancy syntax because it feels more aligned
> with other Boost and standard library components. Having 'reset' also
> allows not to include boost/none.hpp.
>

The standards committee's library enhancements working group (LEWG) agrees
with you. Nevin's question came up in the context of aligning several
Library Fundamentals TS functions with each other and the rest of the
standard library. The proposal is progressing and will likely be part of
C++17.

--Beman