Re: [Boost-users] [statechart] Passing parameters from event to State Local Storage

Subject: Re: [Boost-users] [statechart] Passing parameters from event to State Local Storage
From: Felipe Magno de Almeida (felipe.almeida_at_[hidden])
Date: 2010-05-06 13:00:59

Christophe Bourez <boost_at_[hidden]> writes:

> I need to maintain a parameter into the state local storage. This
> parameter is initially contained in the event that causes the transition to
> the target state. I give hereafter a small illustrative example.
>
> typename sc = boost::statechart;
>
> class EvTest : public sc::event<EvTest>
> {
> public:
>     EvTest(std::size_t val) : value(val) {}
>     std::size_t getValue() const { return this->value; }
> private:
>     std::size_t value;
> };
>
> class MyStateMachine;
> class StSource;
> class StTarget;
>
> class StSource : public sc::simple_state<StSource, MyStateMachine>
> {
> public:
>     typedef sc::custom_reaction<EvTest> reactions;
>
>     sc::result react(const EvTest &event)
>     {
>         // How to pass event.getValue() to the target state ?
>         transit<StTarget>();
>     }
> };
>
> class StTarget : public sc::simple_state<StTarget, MyStateMachine>
> {
> public:
>     StTarget(std::size_t val) : val(value) {}
> private:
>     std::size_t value;
> };

I have a patch using boost.fusion to allow this. It works this way:

class StSource : public sc::simple_state<StSource, MyStateMachine>
{
public:
    typedef sc::custom_reaction<EvTest> reactions;
    sc::result react(const EvTest &event)
    {
        // How to pass event.getValue() to the target state ?
        transit<StTarget>(event.value); // pass arguments to target
                                        // state constructor
    }
};

Does Boost have interest in this?

> Thanks,
> Christophe

Regards,
--
Felipe Magno de Almeida