Re: [Patch] Use variadic templates for tr1::is_function

[Doug Gregor <dgregor at cs dot indiana dot edu>]

On Apr 10, 2007, at 3:57 PM, Paolo Carlini wrote:

> ... but then why we have:
>
>  /**
>   * @if maint
>   * Retrieve the result type for a function type.
>   * @endif
>   */
>  template<typename _Res, typename... _ArgTypes>
>    struct _Weak_result_type_impl<_Res(_ArgTypes...)>
>    {
>      typedef _Res result_type;
>    };
>
> in the first place? Does it ever trigger? (Still, the other  
> specializations, for function pointers and references, should be  
> added of a version for variadic functions, I think)

_Weak_result_type_impl is used directly from _Weak_result_type, like  
this:

  /**
   * @if maint
   * We already know the result type for @c Functor; use it.
   * @endif
   */
  template<typename _Functor, typename... _ArgTypes>
    struct _Result_of_impl<true, _Functor(_ArgTypes...)>
    {
      typedef typename _Weak_result_type<_Functor>::result_type type;
    };

So, we end up stripping off the argument types (_Argtypes...) that  
are passed to the _Functor, and only _Functor gets passed on to  
_Weak_result_type_impl.

	Cheers,
	Doug