Re: [Boost-users] [statechart] Substates in dll

Subject: Re: [Boost-users] [statechart] Substates in dll
From: Andreas Huber (ahd6974-spamboostorgtrap_at_[hidden])
Date: 2009-07-15 10:38:08

[snip]
> What would happen if we wanted this to scale to more states, so
> that e.g. there's a State3 that we transition to in response to EvAnother?
> And so on with more states and events, where we'd like each of State3,
> State4, etc. to be implemented in their own dll. It would seem that we'd
> have to build up a hierarchy where we have one inheritance level for each
> state.

Not necessarily. It is usually enough when you enable client code to supply 
one or more *parts* of a state machine, each part containing as many or as 
few states as necessary. As I showed in the last post, you can use virtual 
functions whenever you want to transit to a state of such a client-supplied 
part and make those states visible to which client-supplied parts need to 
make transitions. I personally haven't used this very much, but it seems 
inheritance hierarchies should stay rather shallow this way.

This approach sort of resembles the template method pattern.

Regards,

--
Andreas Huber
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