Re: [boost] Review manager needed for TTI library

Subject: Re: [boost] Review manager needed for TTI library
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-05-10 08:12:04

On 5/10/2011 4:14 AM, Thomas Heller wrote:
> On Mon, May 9, 2011 at 10:16 PM, Edward Diener<eldiener_at_[hidden]>  wrote:
>> On 5/9/2011 2:59 PM, Thomas Heller wrote:
>>>
>>> On Monday, May 09, 2011 08:39:33 PM Edward Diener wrote:
>>>>
>>>> I am looking for a review manager for my TTI library in the review queue.
>>>>
>>>> The TTI library, which is an abbreviation for the 'Type Traits
>>>> Introspection' library, allows a programmer to introspect at compile
>>>> time the inner elements of a C++ type. The introspection process depends
>>>> on specifying the name of the inner element by different macros for
>>>> different types of elements, and then using a generated metafunction to
>>>> determine whether that element exists within the enclosing type. The
>>>> inner elements which can be introspected are type, class template,
>>>> member data, member function, static member data, and static member
>>>> function.
>>>
>>> Short query about a specific feature I am interested in.
>>> Will your library enable the following usecase:
>>>
>>> struct foo
>>> {
>>>      template<typename Sig>
>>>      struct result;
>>>
>>>      template<typename This, typename A0, typename A1>
>>>      struct result<This(A0, A1)>
>>>      {
>>>          typedef A0;
>>>      };
>>> };
>>>
>>> struct bar
>>> {
>>>      template<typename A0, typename A1>
>>>      struct result<A0, A1>
>>>      {
>>>          typedef A0;
>>>      };
>>> };
>>>
>>> has_old_result<foo, A1, A2>::type // evaluates to false
>>> has_old_result<bar, A1, A2>::type // evaluates to true
>>>
>>> also supporting "variadic" result_of protocol detection.
>>> I failed to come up with a generic solution to that particular problem.
>>> Would be
>>> awesome if you solved it :)
>>
>> I do not understand what you are doing above. Maybe if you explained what
>> you are trying to do I can answer.
>
> I just want to check whether a functor supports the Phoenix V2 result protocol
> or the boost::result_of protocol. "foo" is implementing
> boost::result_of and "bar"
> is implementing the Phoenix V2 protocol.
>
>> The TTI library can introspect a type to find out what constructs are nested
>> within that type at compile-time, given the name of the construct at a
>> minimum. That is the full extend of what the library does. The only type of
>> inner construct it can not introspect is a function template, but I explain
>> why that can't be done in the Help.
>
> Yes, this is exactly what i want to do here, check if a nested
> template fullfills
> certain concepts (not really if its there or not), aka introspecting
> the (possible)
> specializations of a nested result type.

The TTI library can check if a nested class template has a given 
signature, but not if it also has some nested specialization. I think 
you also want the ability to check if a class template itself has some 
nested constructs where the TTI library only checks the nested 
constructs of a type.