Re: [boost] [optional] operator<(optional<T>, T) -- is it wrong?

Subject: Re: [boost] [optional] operator<(optional<T>, T) -- is it wrong?
From: Vladimir Batov (Vladimir.Batov_at_[hidden])
Date: 2014-11-25 22:44:50

On 11/26/2014 02:33 PM, Edward Diener wrote:
> On 11/25/2014 10:20 PM, Matt Calabrese wrote:
>> On Tue, Nov 25, 2014 at 5:27 PM, Edward Diener <eldiener_at_[hidden]>
>> wrote:
>>
>>> On 11/25/2014 7:18 PM, Vicente J. Botet Escriba wrote:
>>>>
>>>> Following your reasoning, I will suggest to remove the implicit
>>>> construction from T to optional<T> and/or remove the
>>>> operator<(optional<T>, optional<>). If we can not live without 
>>>> them, we
>>>> could always try to do whatever is better.
>>>>
>>>
>>> I do not understand why anyone feels that the less than operator for
>>> boost::optional<T> is wrong.
>>
>>
>> I can MAYBE see not having them as long as std::less and family are 
>> still
>> specialized accordingly (specializing std::less is [correctly, IMO] 
>> in for
>> the proposed standard optional now anyway, thanks to Tony Van Eerd).
>> Ultimately, though, I really don't think there's a problem with also 
>> having
>> the operators overloaded. I simply don't buy the "gotchas."
>
> If the C++ standard says that associative container of std::optionals 
> is fine but some programmers believe that manually comparing them via 
> the less than operator is not fine, I think we have a real conceptual 
> problem here, even outside of the mere non-orthogonality of the 
> situation.

The discussion is not about

     op<(optional<T>, optional<T>)

but rather

     op<(T, optional<T>)