signal_type::arg<0>::type

Thanks. Originally I tried the following: #include #include int main() { boost::signals2::signal onEvent; typedef BOOST_TYPEOF(onEvent) OnEvent; typedef OnEvent::first_argument_type first; } And it doesn't compile (MSVC9.0) Note that if I add 1 argument, it does compile: //... boost::signals2::signal onEvent; typedef OnEvent::first_argument_type first;

first_argument_type/second_argument_type only exist for 2 argument signals. 1 argument signals just have argument_type.  IIRC, thats how stuff in the functors in the STL look.

Oh, I see. Actually, I missinterpreted its description - I thought that first_argument_type should exist if the signal has *at least* 1 argument. Thanks again.