Re: [Boost-users] Using SFINAE to detect presence of member function - Unreliable

3 Feb 2009

      2009/2/2 Naik, Roshan <roshan.naik@hp.com>
...
Seems like the following specialization of impl<> works:
template <typename r>
struct impl<true, r(void)>
{
static const bool value =
sizeof(
return_value_check<type, r>::deduce( (
(((derived_type*)0)->operator()(),
details::void_exp_result<type>())
) )
) == sizeof(yes);
};
I don't think it does. Try this test:

struct foo {
   void operator()() const {}
};

int main() {
  is_call_possible<foo, void()>::value;
}

Roman Perepelitsa.