on Sun Aug 17 2008, Andrey Semashev <andrey.semashev-AT-gmail.com> wrote:
David Abrahams wrote:
on Sun Aug 17 2008, Andrey Semashev <andrey.semashev-AT-gmail.com> wrote:
State machines, as I see it, are meant to define an object behavior, IOW reduce the amount of undefined behavior. It is pointless to use them to implement undefined behavior.
So std::vector is pointless because it exhibits undefined behavior when misused?
No, vector is not pointless, because its purpose is to store elements, not to define behavior.
Sorry, but you're making no sense to me. The defined behaviors of vector are just as important as the defined behaviors of your FSM library.
I will need vector to store elements even with undefined behavior on invalid pointers as its input. But why would I need FSM if it doesn't define my object's behavior?
Well, it would define useful behaviors for valid inputs.
Or if I am adamant on what particular input will come from the environment (IOW, the behavior is already defined by the environment)?
The OP's assumption only works when you have sufficient control over the inputs.
I find the code written using the proposed library rather procedural in nature (rather than declarative), thus the OP's comparison is very apt from my point-of-view. The hand-rolled code actually looks clearer and more direct to me. Please, have a look at my reply to Phil. I've attached a code snippet with a transition map. Does that look more declarative?
Not really, to me. It's very difficult for me to see the transitions in that code. Compare that with either of my player examples.
Hmm... I don't see much difference, except for comments markup. Both code samples use transition maps, both use vectors... Is it because the transition map in your code is a member of the complete FSM?
Sorry, I don't know what a "transition map" is. In fact, when I google ``fsm "transition map"'' all the top hits come from your library, which tells me it's almost certainly not a known term in the FSM domain. I'm talking about a State Transition Table (STT) (http://en.wikipedia.org/wiki/State_transition_table). The STT in my code is clearly visible at http://svn.boost.org/trac/boost/browser/trunk/libs/mpl/example/fsm/player1.c... Where's yours? -- Dave Abrahams BoostPro Computing http://www.boostpro.com