New API in libsigc++ 3.8

Member sigc::signal_connect (signal< T_return(T_arg...)> & signal, T_return(* fun)(T_arg...))

Member sigc::signal_connect (signal< T_return(T_arg...)> & signal, T_obj & obj, T_return(T_obj::* fun)(T_arg...))

Member sigc::signal_connect (signal< T_return(T_arg...)> & signal, const T_obj & obj, T_return(T_obj::* fun)(T_arg...) const)