Re: [boost] [msm] orthogonal region and event consume

Subject: Re: [boost] [msm] orthogonal region and event consume
From: Takatoshi Kondo (redboltz_at_[hidden])
Date: 2012-05-26 10:43:01

Hello,

I wrote a patch.
If an event that corresponds to the transition from an entry pseudo
state is not equal to boost::msm::front::none,
then do self->process_event(evt.m_event);
Else doesn't do it.

This patch brings dependency that from msm::back to msm::front. If it
is not suitable, msm::front::none may move to msm/common.hpp.

Thanks,
Takatoshi

On Sat, May 26, 2012 at 3:40 PM, Takatoshi Kondo <redboltz_at_[hidden]> wrote:
> I analyzed this problem deeply. It doesn't relate to orthogonal regions.
> My understanding is that Boost.Msm requires the same event for
> transitions that to entry pseudo state and from entry pseudo state.
> So,  in simple_entry.png(attached diagram), the transition from Entry1
> requires Event1.
>
> But this requirement is sometimes problematic. Because submachines
> sometimes shouldn't know the outside information such as Event1. So, I
> chose msm::front::none instead of Event1 (entry_pseudo_event.cpp).
>
> msm::front::none event approach has two problems. One is preserving
> outer event. And then the event is handled similar as the deferred
> event. The other is there is no way to get the outer event in the
> submachine.
>
> I believe that the former should be fixed. But I found another solution.
> See the entry_pseudo_event_template.cpp.
>
> The event that corresponds to the transition from the entry pseudo
> state is injected as a template parameter. So, submachine doesn't need
> to know the Event1.
> This approach solves the both above problems.
>
> Thanks,
> Takatoshi
>
> On Fri, May 25, 2012 at 5:48 PM, Takatoshi Kondo <redboltz_at_[hidden]> wrote:
>> Hello Christophe,
>>
>> I'm using Boost.MSM version 1.49.0. I bumped on a suspicious behavior.
>> See the attached diagram and code. When Event1 occurs in State1,
>> Action1 is invoked.
>>
>> I think the event isn't consumed correctly.
>>
>> If the transition from State1 to State2 connect State2 directly
>> instead of Entry1, the event seems to be consumed.
>>
>> What do you think?
>>
>> Thanks,
>> Takatoshi