void CL_Callback_0< RetVal >::set( RetVal(*)() function); void CL_Callback_0< RetVal >::set( RetVal(*)(UserData) function, const UserData & user_data); void CL_Callback_0< RetVal >::set( InstanceClass * instance, RetVal(InstanceClass::*)() function); void CL_Callback_0< RetVal >::set( InstanceClass * instance, RetVal(InstanceClass::*)(UserData) function, const UserData & user_data);