Re: [Boost-users] [boost-users][StateChart]

Hi Igor

1. IIUC, in async_state_machine it's impossible to post an "internal" event from a state by calling queue_event(), as noone will actually call process_event().

asynchronous_state_machine<>.queue_event() does not exist. IIUC, then you simply want to post an event, no? That is, at some point while an event is being processed (e.g. in an entry action, in a transition action, etc.) you want ensure that another event will be processed right after the machine is done with the current event? In that case, simply call simple_state.post_event(), please see http://www.boost.org/doc/libs/1_35_0/libs/statechart/doc/reference.html#post...

Instead, it should be always done through the processor queue, like this: outermost_context_type &machine = outermost_context(); machine.my_scheduler().queue_event(machine.my_handle(), MyEvent()); Am I right?

It depends. What you describe here ultimately has the same effect as calling simple_state<>.post_event(), with one crucial difference: In the first approach the posted event has absolute priority over events in the fifo_scheduler queue. In the second approach the event is put into the same queue as external events, with the effect that an event from the outside could be processed before event you queued from inside the machine. Usually (but not always) you want the first behavior.

2. Deferred events in async.machine. Say, we've got the following states (simplified code):

struct State1 : simple_state<...> { typedef transition reactions; };

struct State2 : simple_state<...> { typedef mpl::list < transition, deferral<EvGotoState2>

...

reactions; };

Both events are queued to the machine from the "outer world". * We're already in State2. * We get a bunch of EvGotoState2 posted (eg., 10 events). All of them are queued to the state's deferred events queue. * EvGotoState1 comes. The machine goes to State1 and then immediately consumes 1 deferred EvGotoState2 and move to State2. What happens to the rest of the deferred events? Are they queued again to the deferral queue of State2?

Yes.

3. Is it possible to clear all the deferred events?

Not explicitly.

Is it possible to clear deferred events of a specific type? Eg., in State2 I'd like to alway defer only the *last* EvGotoState2, discarding all the previous deferred events of this type. Is it possible?

Not explicitly. Currently you'd have to use tricks to achieve such behavior. HTH, -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.