Christophe Henry wrote:
Transitions can be either internal or external. Even for simple states. An internal transition in a simple state will never execute exit or entry code.
I didn't find this in the standard, but I might have missed it out. Whatever, after a lengthy discussion with Juraj Ivancic, I came to the conclusion that MSM needed what we called an "execution row", which is pretty much your internal transitions for simple states.
I'll need to search the archives for this discussion (unless it was elsewhere). As for the standard: using the UML 2.2 Superstructure document (it is the one I have handy), Section 15.3.15 describes TransitionKind. There are two constraints listed: 1. source state for "local kind" must be a composite state, 2. source state for "external kind" must be a composite state. No constraint such as this is made for "internal kind". Additionally the Semantics for "internal kind" work fine with simple state and are not constrained.
And this is where I was unclear. A better question would be: For a simple state, how do I create an internal transition?
For the moment, you can't easily. The only way would be to specialize on_entry and on_exit on some events, but this is less than perfect, so this feature is quite at the top of my list.
For now I'll make composite states when I need an internal transitions. <snip>
I don't know about that change, but I know that this depth-first strategy has some critics (which I failed to understand). Whatever, after the new type of row for simple states is added, you'll be able to define it wherever you want in the transition table and can therefore decide yourself of the priority. You will not however be able to do it for rows coming from composites because MSM will handle it alone, otherwise it'd break the exit points. I think it is a reasonable solution.
I agree. The solution sounds reasonable. Thank your for being so responsive. michael -- ---------------------------------- Michael Caisse Object Modeling Designs www.objectmodelingdesigns.com