Hi, I am looking for a static list of types, albeit one in which the order of types does not matter. I have looked into the Metaprogramming library (MPL) and some related work in BGL on property lists, but could not find anything that would make the list unordered (though they do provide a static type-list). To clarify what I mean, using the MPL: typedef boost::mpl::vector<float, int> type1; typedef boost:mpl::vector<int, float> type2; the above usage makes type1 and type2 distinct types since the ordering of types matters. Is there a library compenent with which I can construct a static list of types (just like usage of boost:mpl::vector above) and can query for presence or absence of a type, making the order irrelevant? Furthermore, I would prefer this presence/absence check to be resolved compile-time. The reason for this requirement is that I wish to use this presence/absence test as means by which the compiler can call the appropriate specialized functions for this static list. thanks, Nagender