AMDG Claude Brisson wrote:
I need to enable only if a type T is among a specific known list.
I tried to build an operator is_one_of< T, list of known types > condition that could be used within an enable_if (like others type_traits operators), like this:
or< is_same< T, type1 >, or< is_same< T, type2>, ... >
so I searched for an or< condition1, condition2> construct and didn't find anything...
It's boost::mpl::or_ (Note that or is a keyword) However, in this case, it's easier to use mpl::set: #include <boost/mpl/set.hpp> #include <boost/mpl/has_key.hpp> #include <boost/utility/enable_if.hpp> namespace mpl = boost::mpl; template<class T> typename boost::enable_if< mpl::has_key<mpl::set<int, char, bool>, T>
::type f(const T&) {}
int main() { f(1); // ok f("test"); // fails } In Christ, Steven Watanabe