Hi, I have a mpl::vector of types. Each of the types in the vector have themselves another nested mpl::vector that is a sequence of enums. I have include the code below. What I am trying to do is take the original sequence and make a new sequence based on the predicate that only elements with certains enums in their nested vector be included in the new sequence. I have included more notes in the embedded comments. I was thinking of using mpl::copy_if but am having trouble getting the predicate right. Wanted to know if anyone could steer me in the right direction. I am trying to fill in the ??? below. I am having trouble writing a custom predicate. Thanks in advance. Regards, Bruce #include <string> #include <iostream> #include #include #include #include #include #include #include #include #include #include #include #include namespace mpl = boost::mpl; using namespace mpl::placeholders; enum colors { red, blue, green, yellow }; template<typename COLORTYPES> struct TestClass { typedef COLORTYPES colortypes; }; void func() { // come up with a interface to simplify this like vector_c - only it must be able to handle enums - I would think one would already exist typedef mpl::vector< mpl::integral_c , mpl::integral_c , mpl::integral_c

colorcoll1;

typedef mpl::vector< mpl::integral_c , mpl::integral_c

colorcoll2;

typedef mpl::vector< mpl::integral_c

colorcoll3;

typedef mpl::vector testvector; std::cout << " SIZE IS " << mpl::size<testvector>::value << std::endl; // would like to make a new vector from testvector that contains only those types that have green in their nested vector colortypes. //In other words, go from testvector which has three types to a vector that only has TestClass<colorcoll1> and TestClass<colorcoll3> // typedef mpl::copy_if::type testvectorwithgreen; // I can do it successfully when operating directly on the container as below, but am having trouble deterimining the predicate for the above case typedef mpl::vector_c intColl; std::cout << mpl::size<intColl>::value << std::endl; typedef mpl::copy_if > >::type newIntColl; std::cout << mpl::size<newIntColl>::value << std::endl; } int main() { func(); return 0; }