Re: [boost] Formal Review Request: TypeErasure (docs, Concept Maps misnamed?)

Subject: Re: [boost] Formal Review Request: TypeErasure (docs, Concept Maps misnamed?)
From: Larry Evans (cppljevans_at_[hidden])
Date: 2012-06-21 21:00:14

On 06/21/12 13:17, Steven Watanabe wrote:
> AMDG
>
> On 06/21/2012 10:34 AM, Larry Evans wrote:
>>
>> The page:
>>   */libs/type_erasure/doc/html/boost_typeerasure/conceptdef.html
>> uses the term 'primitive concept':
>>
>>   A primitive concept must be a specialization of a class template,
>>   with a static member function called apply.
>>
>> What's the difference between a 'Concept Map' and 'primitive concept'?
>> If they are the same, why not use the same term for both?
>> [snip]
>>
>
> They aren't the same.  A primitive
> concept specified the interface and
> (optionally) a default Concept Map.
> A Concept Map specifies how a specific
> type models the concept.
>

Would not:

  template<class T = _self, class U = T>
  struct less_than_comparable
  {
      static bool apply(const T& lhs, const U& rhs) { return lhs < rhs; }
  };

from:

http://svn.boost.org/svn/boost/sandbox/type_erasure/boost/type_erasure/operators.hpp

satisfy the definition you give above for a primitive concept:

  A primitive concept specified the interface and
  (optionally) a default Concept Map.

Where the optional default Concept Map is the general template, as
shown in the above operator.hpp.  Somehow, I assume by "specified the
interface" you mean, somehow, the specialization idea:

  A primitive concept must be a specialization of a class template,
  with a static member function called apply.

from:

  */libs/type_erasure/doc/html/boost_typeerasure/conceptdef.html

IOW, an example of "specified the interface" would be the
specialization of less_than_comparable,
  less_than_comparable<std::type_info>
shown here:

*/libs/type_erasure/doc/html/boost_typeerasure/concept.html#boost_typeerasure.concept.concept_map

Of course, I could be completely wrong; hence, could you be more
specific about what you mean by "specified the interface" and
"(optionally) a default Concept Map"?

I can't help but draw the conclusion that a "Concept Map" is simply
the general template and all specializations of a:

  class template, with a static member function called apply

as mentioned in conceptdef.html; however, I also feel that's way too
simple. What am I missing?

TIA.

-regards,
Larry