Re: [boost] [MSM] Is there any interest in C++14 Boost.MSM-eUML like library which compiles up to 60x quicker whilst being a slightly faster too?

Subject: Re: [boost] [MSM] Is there any interest in C++14 Boost.MSM-eUML like library which compiles up to 60x quicker whilst being a slightly faster too?
From: Kris (krzysztof_at_[hidden])
Date: 2016-02-02 17:02:34

On Tue, Feb 2, 2016 at 9:55 PM, Klaim - Joël Lamotte [via Boost] <
ml-node+s2283326n4683151h0_at_[hidden]> wrote:

> On 2 February 2016 at 22:29, Krzysztof Jusiak <[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=4683151&i=0>> wrote:
>
> > On Tue, Feb 2, 2016 at 7:09 PM, Klaim - Joël Lamotte <[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=4683151&i=1>>
> > wrote:
> >
> > > On 2 February 2016 at 19:41, Vicente J. Botet Escriba <
> > > [hidden email] <http:///user/SendEmail.jtp?type=node&node=4683151&i=2>>
> wrote:
> > >
> > > >
> > > > I see that MSM eUML defines the transitions like
> > > >
> > > > target == source + event [guard] / action
> > > >
> > > > but MSM-lite reverse the source and target
> > > >
> > > > src_state == dst_state + event[ guard ] / action This is confusing.
> > > >
> > > > Why have you chosen this syntax? Vicente
> > > >
> > > >
> > >
> > > Same question here. I misread the examples at first because the
> meaning
> > is
> > > reversed.
> > > It feels unnatural that the state you are going to is part of the
> > > expression stating the conditions to get there.
> > >
> > > The MSM syntax is clearer to me at least.
> >
> >
> > I see your point. It seems like I will have to change the default
> behaviour
> > then as it's clearer for most devs. Guess, I'm the ackward one here.
> > Please, check the euML emulation example ->
> >
> >
> http://boost-experimental.github.io/msm-lite/examples/index.html#euml-emulation
> > as DSL
> > behaviour might be changed if it comes to states order by defining
> > BOOST_MSM_DSL_DST_STATE_FIRST.
> >
> > If it comes to the transition table DSL. I was concidering a lot of
> > options. For example MSM3(eUML2) is using src + event [guard] / action
> ->
> > dst
> > which looks great, however, having a dst state at the end is not really
> > practical, especially after a lot of noice introduced by guard and
> actions
> > (for example in place lambda expressions).
> >
> > Right now, I'm thinking of introducing DSL which would look like that.
> >
> > make_transition_table(
> >   "idle* -> state1"_t + event [ guard ]  / action
> > , "state1 -> X"_t  [ guard ]  / action
> > );
> >
> > Nevertheless, I'm not sure whether such approach would be seen
> positively
> > because following MSM approach it should be more like that.
> >
> > make_transition_table(
> >   "state1 <- idle*"_t + event [ guard ]  / action
> > , "X <- state1"_t  [ guard ]  / action
> > );
> >
> > which looks confusing for me. Any thought on this?
> >
> >
> I was going to suggest <= and => but I don't know the potential problems.
>

It's a compile time string parsing so there are no issues with characters
here, just the design.
So your suggestion would be:

// *=initial

"state1 <= idle*"

or

"idle* => state1"

is that correct?

'->' was chosen, simply because it might be found in the UML2
specification, but there are no limitations here. Whatever works the best.

Thanks for the suggestion, Kris

>
> > Thanks for your feedback,
> > Cheers, Kris
> >
> >
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