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From: Andreas Huber (ah2003_at_[hidden])
Date: 2004-05-28 02:10:52

E. Gladyshev wrote:
> From: "Andreas Huber" <ah2003_at_[hidden]>
> [...]
>> Unfortunately, all FSM standards/publications I know are absolutely
>> silent on error handling.
> I can understand why.
> If you are referring to "error" as something unexpected,
> then it is out of the state machine realm.

If the errors were unexpected it would make little sense to handle them in
the state machine, right?

> The state machine mantra is complete behavioral determinism.
> If "error" is an expected condition, then it is just a normal
> event that is part of the state machine design.

When an entry action fails, you have the problem that the state machine is
unstable because it would be a bad idea to just continue to enter other
(inner) states (see Rationale). Since it is non-trivial to define what to do
in such a situation, I think it is unfortunate that all these standards are
silent on error handling. They implicitly force you define all your entry
and transition actions in a way so that they can never fail.



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