Re: [boost] FSM Review Announcement

From: Chris Knight (cknite_at_[hidden])
Date: 2008-08-06 18:44:39

On Wednesday 06 August 2008 1:18:33 pm Andrey Semashev wrote:
> Chris Knight wrote:
> > template< typename T > void on_process(T const&);
> >
> > void on_process_dynamic(base_event const& base)
> > {
> >         base->some_virtual();
> >         // or
> >         m_events[base->id].some_non_virtual();
> > }
> >
> > My only point was that with a little bit of help from the library,
> > implementing dynamic/defferred event processing should be possible.
>
> Sorry, I still don't get it. You already can pass events with virtual
> functions and process them through base classes. The main problem with
> deferred events is that there's nobody to call process(deferred_event)
> of the FSM. Another problem is that you generally don't know the
> complete FSM type in states or transitions, but this issue is solvable
> with a change in the state and transition base classes.
>
> Could you elaborate your point, please?

I think you basically have it. I agree that the deferred event processing
while (events_to_process) { fsm.process_dynamic(event); } shouldn't be 
included in boost.FSM, the process_dynamic(event_c& const) function should 
be.

Using the TagV in the event_c class, it should be possible to provide a member 
function in state_machine to process events given only a reference to the 
event_c base class and that calls the appropriate process(event& const) via 
dispatching on the integer TagV. 

I'm trying to figure out whether this would be a simple feature addition or 
there is some critical piece I am missing. 

Chris