[Boost-users] Type arithmetic library?

Hello, boost typeof library can automatically deduce the type. But I'm interested in finding the nested type. For example, if I have a template S<T1, T2>. I'd like to deduce that it has two template arguments, I'd like to access its template argument by index (say, 0 and 1 for this case). I did a preliminary search, but found no such facilities. I may overlook something. Would you please let me know if there is such a facility in boost? -- Regards, Peng