Hi all, Say I have a functor which accepts a tag instance: struct tagA {}; struct tagB {}; struct MyFunc { template <typename TTag> void operator()(TTag, int other_stuff) {...} }; In some cases I want to pass multiple tags at once. Is it safe to just instantiate mpl::pair, mpl::vector, etc. and use them for this purpose, since from a runtime perspective they're just empty classes? Or, is this a Bad Idea for some reason? Thanks, -Gabe