Hi all, I'm trying to use mpl::remove to do some processing with a template parameter, like this template struct my_class { typedef mpl::vector my_vector; typedef mpl::remove::type my_non_vector; //failed here }; Compiler report that my_vector is not derive from my_class. It seems that 'remove' would test the sequence at once, and my_vector still un_known yet, so it fails, is this guess right? //-------------------------------------------------------------------------- And I've tried this fusion too: teypdef vector vec; vec v; fusion::for_each; it seems that it iterate 4 times, not 2, even size(vec) return 2. It seems only evaluate will skip null_type, iterate will go through all member, is my guess right? Best Regards Spider