Le 02/02/2016 22:12, Krzysztof Jusiak a écrit :
On Tue, Feb 2, 2016 at 6:19 PM, Vicente J. Botet Escriba < vicente.botet@wanadoo.fr> wrote:
Le 01/02/2016 11:57, Kris a écrit :
Hi, IIUC you are proposing a 3rd MSM library in Boost, and you don't pretend to make it a sub-library of Boost.MSM. If I'm right, I suggest you to rename the namespace to msm_lite or whatever you find more appropriated.
Fair point, thanks for pointing it out. It's a valid concern. I have nothing against changing the namespace/name as 'msm-lite' is just a working title either way. Not sure what the best name should be tho? Well, you would need to choose a name ;-)
Well these are already quite a few features. I have not see local transitions (different from internal transitions).
Yea interna(local) transitions are supported. Example here -> http://boost-experimental.github.io/msm-lite/examples/index.html#transitions
Internal and local transitions are not the same. How do you make syntactically the difference. I've not see and reference to local transitions.
Please could you point me if you support choice points?
While choice points are unavoidable in graphical UML, I find it not very
useful while writing MSM in C++ as I prefer to do it using if or switch. However having a transition table that can have only one next-state by transition disable this possibility. I use to have a transition table with a transition that has an action_nextstate that do the action and returns the nextstate of the transition.
|"s2"_s + event<e2> [ guard ] / action_nextstate This avoids the storage of local variable on the MSM data context. |
Have you considered this possibility?
Interesting idea, can you elaborate please as I'm not sure whether I follow the idea with the action_nextstate? If it comes to the choice points, I guess the easier way is just to have multiple transitions from the same state?
make_transition_table( s1 -> s2 + e2 [some_guard1 && some_guard2] / action1 , s1 -> s3 + e2 [other_guard] / action2 , s1 + e2 / action3 );
would be the same as
if (e2) { if (some_guard1 && some_guard2) { action1; change_state_to(s2); } else if(other_guard) { action2; change_state_to(s3); } else { action3; } }
This is almost the idea. But the use case is the followings, sorry I will use the src + evt / act = dst notation make_transition_table( s0 + e / action0 -> cp cp [some_guard1] / action1 -> s1 cp [else] / action2 -> s2 ); With action-next-state transition could be s0 + e / action_nextstate where action_nextstate is auto action_nextstate = [](auto const& evt) { action0; if (some_guard1) { action1; next_state(s1); // You could also return a state if there is a type that can store any state of the state machine. } else { action2; next_state(s2); } } Note that these action-nextstate could define some local variables in action0 that can be used in some_guard1 and in action1 and action2 . The uml transition schema forces to store these local variable on the state machine context (or a state context if supported), which is less than optimal. This is needed because there is no way to share variables between the action0, some_guard1 and in action1 and action2. In addition action1 and action2 have no access to the event e, as only the action0 has it as parameter. Do you think that this kind of transitions goes against the UML semantics? Best, Vicente