[c++-concepts]

[Andrew Sutton]

I presented that at C++Now, so I hope so :) It lets me write:

template<typename T>
  requires Input_iterator<T> // no parens!
    void f(T x);

Walter Brown also suggested this usage in his object alias paper.

In concepts lite, a concept is essentially an expression. Thus far,
we've packaged those expressions in constexpr functions (using
"concept" as a declaration specifier to impose additional
restrictions). Variable templates fall easily into this same set of
restrictions. Plus, no overloading.

Andrew

On Thu, May 30, 2013 at 3:34 PM, Jason Merrill <jason@redhat.com> wrote:
> On 05/30/2013 03:17 PM, Andrew Sutton wrote:
>>>
>>> | -  /* 1 spare bit */
>>> | +  unsigned concept_p : 1;                  /* var or fn */
>>> | +  /* 0 spare bit */
>>> |  };
>>>
>>> Hmm I don't understand the comment "var or fn".
>>> If it is declared a concept, how can it it be a var?
>>
>>
>> Copied from the other bits in the class. I think it means it applies
>> to either variables or functions. I left it that way in anticipation
>> of template variables.
>
>
> Can template variables be concepts?
>
> Jason
>



-- 
Andrew Sutton
andrew.n.sutton@gmail.com