David Abrahams wrote:
>  "Andreas Huber" <ah2003@[...].net> writes:
> 
> > Assumptions:
> > A1. When a state machine object is destructed, the modeled state
> > machine must also be terminated (i.e. the destructor of the state
> > machine unconditionally terminates the state machine before
> > returning to the client).
> 
>  I've got a problem with that assumption.  It seems to be an
>  association made because of a conflation of C++'s notions of
>  termination with the UML standard's use of the word "terminate" to
>  denote something unrelated, at least as you described it in snipped
>  text.

I suspected that we will disagree on this.

> > A2. If an exit action fails, the state associated with the exit
> > action has not been left.
> 
>  I'm fine with that assumption.  In fact, that seems provable.

Yes, I realized that after posting. F1 provides strong arguments for A2.

> > Moreover, one could also question whether the UML standard should
> > have any bearing for an FSM library that implements behavior that is
> > not covered in the standard (i.e. exit action failures). I see
> > failing exit actions as an addition or enhancement to the behavior
> > defined in the standard. If such an enhancement breaks the behavior
> > defined in the standard, I think the enhancement should be rejected.
> 
>  Another thing I should mention: the finite state machine abstraction
>  was around long before UML and will stay around long after UML has
>  crumbled to dust because of its overbearing weight and its OO
>  orthodoxy <wink>.

:-)

>  Actually I think that UML _state charts_ seem like
>  a pretty good representation, but I'm not sure that I would want to
>  read the UML spec like a bible when approaching the project of
>  building a C++ state machine framework.

I'm reading it like a bible only when it helps to argue my case ;-).
Otherwise boost::fsm takes many (hopefully undisputed) diversions from the
UML standard (see http://tinyurl.com/33vht, UML to boost::fsm mapping
summary).

Regards,

Andreas


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