On Fri, 12 Aug 2011, Mostafa wrote:
On Fri, 12 Aug 2011 02:31:10 -0700, John Maddock <boost.regex@virgin.net> wrote:
From your description, I think I've done exactly this. E.g.
--8<---------------cut here---------------start------------->8--- template <class U> struct X { // member function void f(int) becomes something like: template <class T> typename enable_if< mpl::and_< is_convertible<T,int> , some_condition_on<U> > >::type f(T x_) { int x = x_; ... } }; --8<---------------cut here---------------end--------------->8---
That works as long as the function has at least one parameter that can be turned into a template, but I have some cases that are operators or else have no parameters.
In case of no-parameter functions or operators, what's wrong with:
template <class U> struct T { void f() { f_impl(<static_cast<void *>(0)); }
private: template <class T> typename enable_if< mpl::and_< is_convertible<T, void *>, some_condition_on<U>
::type f_impl(T) { .... } };
In that case, f would not be covered by SFINAE, since it is not a template. Calls to f would fail because of the lack of f_impl, but that would be done after overload resolution. -- Jeremiah Willcock