Seweryn Habdank-Wojewódzki wrote:
Dears // The code belo is not working
#include <boost/type_traits.hpp> #include <boost/static_assert.hpp> #include <boost/utility.hpp>
template <typename B> class test { public: template <typename R> test (R const &) { BOOST_STATIC_ASSERT((boost::is_base_of<B, R>::value)); } };
int main() { test <int> t (static_cast<int>(0)); }
I'm not sure if it's clear from the docs, but the behaviour of is_base_of was changed in the draft std so that it evaluates to true for any is_base_of<T,T>. So if you want to assert that B really is a base class of R, then use: is_base_of<B,R>::value && !is_same<B,R> or is_base_of<B,R>::value && is_class<B>::value Ah, just checked the docs, and it does say: " Note that is_base_of<X,X> will always inherit from true_type. This is the case even if X is not a class type. This is a change in behaviour from Boost-1.33 in order to track the Technical Report on C++ Library Extensions." HTH, John.