on Mon Aug 18 2008, Darryl Green <darryl.green-AT-aanet.com.au> wrote:
On Sun, 2008-08-17 at 22:12 -0800, David Abrahams wrote:
on Sun Aug 17 2008, Darryl Green <darryl.green-AT-aanet.com.au> wrote:
the diagram in the USB example is an incredibly verbose representation (by count of nodes and edges) of what is described by Phils code.
But Phil didn't encode the whole machine represented in the diagram.
No - but most of what he left out was checking for invalid inputs that you have been claiming is not necessarily required. Adding in the suspended state tracking in an ad-hoc way would only need:
bool suspended;
void bus_inactive() { suspended = true; } void bus_activity() { suspended = false; }
yes, well I wasn't expecting such an ad-hoc approach; it's not a very direct translation from the diagram.
Obviously you don't infer from this that any attempt to embed state diagram (like) representations in code is pointless,
I do think it's pointless in C++, although I don't do it by inference from anything you're mentioning.
Wow! Does that mean you are against any FSM library or only one that tries to represent a diagram by some method other than an attributed edge list (state trainstion table)?
Umm, no, I just think there's no reasonable way to draw state diagrams in C++ syntax (outside of comments).
typedef mpl::vector< fsm::transition<Attached, fsm::event<PowerOn>, Powered>, SetAddressTrans<Default, std::not_equal_to, Address>, SetAddressTrans<Address, std::equal_to, Default>, SetConfigurationTrans<Address, std::not_equal_to, Configured>, SetConfigurationTrans<Configured, std::equal_to, Address>, fsm::transition<fsm::any_state, fsm::event<Reset>, Default>, fsm::transition<fsm::any_state, fsm::event<PowerOff>, Attached>
::type Transitions;
The bits enclosed by fsm::transition look like they might be rows in an STT, although they're awfully verbose, with a great deal of surrounding syntactic noise that distracts from being able to read the actual semantics. AFAICT, the other parts do not bear any obvious resemblance to rows in an STT.
I agree that the convenience classes that Andrey put together to encapsulate the data dependend (gated) transitions are irregular. Can you suggest a better approach to deal with them?
not yet, I guess. I don't understand what they do. -- Dave Abrahams BoostPro Computing http://www.boostpro.com