Re: [Boost-users] [MSM] How to access event-attributes through a"kleene"-event?

Subject: Re: [Boost-users] [MSM] How to access event-attributes through a"kleene"-event?
From: Deniz Bahadir (deniz.bahadir_at_[hidden])
Date: 2013-02-21 15:40:17

Hi again,

>
[snip]
>
> // An action which returns the event's number.
> BOOST_MSM_EUML_ACTION(GetEventNumber_)
> {
>     template <class Fsm, class Evt,
>              class SourceState, class TargetState>
>     int operator()(Evt const& evt, Fsm&,
>                   SourceState&, TargetState&)
>     {
>       return evt.getNumber();
>     }
> };
>
>
> // The attribute:
> BOOST_MSM_EUML_DECLARE_ATTRIBUTE(int, EventNo)
> BOOST_MSM_EUML_ATTRIBUTES((attributes_ << EventNo), EventNoAttr)
> // All events that contain this attribute:
> MY_BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES_AND_MEMBERS(event1,
>     EventNoAttr,
>     (int getEventNumber() const {
>        return get_attribute(EventNo);
>      })                                     // <-- members_list
> )
> /* ... more events with same scheme ... */
>
> // Creating an instance of the new "kleene"-event which has
> // a "getNumber" member-function.
> any_number_event number_event;
>
> // The transitions table
> BOOST_MSM_EUML_TRANSITION_TABLE((
>     State1 + number_event
>              [IsEventNumberGT_<7>()]                 == State2,
>     State1 + event1
>              / (fsm_(lastEventNo) = event_(EventNo)) == State3
>     State2 + kleene
>              / (fsm_(lastEventNo) = GetEventNumber_)) == State3
> ), stt)
>

Of course, I had some more typos. (I did not test, what I extracted from 
my code into the email... :-/)

However, I realized, that for my case I do not really need the 
"IsEventNumberGT_<VAL>" action.
I could as well have used the "GetEventNumber_" action in the transition 
table which is even clearer for a C++ developer:

// The transitions table
BOOST_MSM_EUML_TRANSITION_TABLE((
    State1 + number_event
             [GetEventNumber_ > Int_<7>()]    == State2,
), stt)

Ciao,
Deniz

PS: I found a possible bug in MSM when accessing state-attributes from 
actions. But maybe I am doing something wrong. I'll open a new 
email-thread for that with subject "[MSM] Unable to retrieve correct 
value of attribute of a state from within actions. (Possible Bug?)". 
Maybe you could have a look at it.