Re: [boost] Static constexpr map

Subject: Re: [boost] Static constexpr map
From: Agustín K-ballo Bergé (kaballo86_at_[hidden])
Date: 2016-01-16 16:05:27

On 1/15/2016 7:00 PM, Nevin Liber wrote:
> On 14 January 2016 at 22:41, Marshall Clow <mclow.lists_at_[hidden]> wrote:
>
>> On Wed, Jan 13, 2016 at 11:43 AM, Niall Douglas <s_sourceforge_at_[hidden]
>>>
>> wrote:
>>
>>> Sadly, the current proposal for string_view does not provide a
>>> default Traits length function which is constexpr for const char *.
>>> Yes, I find that very daft as a default design choice for a
>>> string_view, but the macro at least makes it not too irritating.
>>>
>>> It uses the existing char_traits classes, which, as you note, are not
>> constexpr.
>> (for some *very odd* reasons).
>>
>> But writing your own traits class that has constexpr len/compare/etc is
>> really, really simple.
>> Maybe I'll do that this weekend, and add it to boost. :-)
>>
>
> Because it gets passed in as a template parameter, it isn't really all that
> general a solution, as it makes your string and string_view types different
> than std::string and std::experimental_string_view.

This is a very good point. However, nothing stops us from internally 
mapping `std::char_traits<CharT>` to 
`boost::detail::constexpr_char_traits<CharT>` when the compiler supports 
C++14 constexpr.

Regards,
-- 
Agustín K-ballo Bergé.-
http://talesofcpp.fusionfenix.com