Re: [boost] [IdentityType] Const omission undocumented.

Subject: Re: [boost] [IdentityType] Const omission undocumented.
From: Lorenzo Caminiti (lorcaminiti_at_[hidden])
Date: 2013-12-03 13:38:35

On Sat, Nov 16, 2013 at 11:18 AM, Mathias Gaunard
<mathias.gaunard_at_[hidden]> wrote:
> On 16/11/2013 01:02, Mostafa wrote:
>>
>> #include <boost/utility/identity_type.hpp>
>> #include <utility>
>>
>> int main()
>> {
>>    BOOST_IDENTITY_TYPE(( std::pair<int,int> const )) x;
>>    // This compiles, so the const qualification in the
>>    // above macro parameter is ignored.
>>    x = std::make_pair(0,1);
>>
>>    return 0;
>> }
>>
>> The omission of const qualification in BOOST_IDENTITY_TYPE types is
>> undocumented. This omission maybe deduced from the documented
>> implementation, but, as noted, that is not part of the library api and
>> is subject to change. I therefore propose that this behaviour be
>> documented as part of the library's public api.
>
>
> That looks like a bug.

Is there a way to extract the cv-qualifier from a function parameter
type at compile-time?

some_mata_function<void (int const)>::type // evaluates to `int const`
not just `int`

Right now I do the following which looses the cv-qualifier (I also
tried to program my own meta-functions but I wan't able to retain the
cv-qualifier).

boost::function_traits<void (int const)>::arg1_type // evaluates to
`int` and not to `int conat` :(

Thanks.
--Lorenzo