Simonson, Lucanus J wrote:
It would be very nice if Boost.Config provided the BOOST_NO_SFINAE_EXPR macro, that would be defined if the compiler does not support SFINAE applied to expressions. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2634.html
GCC supports this feature since 4.4 both for C++03 and C++0x for example. Yes, such a macro is needed
So we could do this instead of use mpl and?
template <typename T1, typename T2> enable_if_c<is_a_A<T1>::value && is_a_B<T2>::value>::type foo();
This doesn't require SFINAE extended to expressions. This already works fine.
Also, it turns out that the ability to provide a default template parameter for function templates markedly clarifies code using enable_if. (I learned this Howard Hinnant, but I think he may have gotten the idea from Peter Dimov.)
This sounds interesting. Can you explain how?
I assume he refers to template< typename T, typename Enable = typename boost::enable_if<...>::type
void foo(T);