"Alexander Nasonov" <alnsn@yandex.ru> writes:
David Abrahams wrote:
Okay, but what's the value of modeling an is-a relationship between states? In a FSM, states are distinct. One state is-not-a nother state.
Dog is-a Animal at modelling state.
Sorry, I don't understand the meaning of "at modelling state." Oh, you mean "at modelling stage?"
At runtime
Dog dog;
is not-a
Animal animal;
Likewise, Running state is-a Active state at modelling stage.
So it's just a way of classifying states with common properties?
AFAICT it seems to be a way of grouping states, or perhaps of emulating substates, so you can avoid writing the transitions that a group of states has in common (?)
Yep.
That's a clever approach to dealing with substates. I'm not sure it works for every case, but then, the details of how substates are supposed to work have always eluded me. I still don't see how you can keep associated data stored in the Active base sub-object alive across all the other active states, at least not without copying it. -- Dave Abrahams Boost Consulting www.boost-consulting.com