Re: [Boost-users] Boost MSM - Ways to send info out from state machine to outside world

Subject: Re: [Boost-users] Boost MSM - Ways to send info out from state machine to outside world
From: gauravk (gaurav_kulkarni_at_[hidden])
Date: 2011-09-08 20:52:03

Hi, 

I had one more question about the lifetime of the FSM. When does the state
machine die? I was expecting that the state machine has to be explicitly
killed (similar to fsm's start() method). But from whatever I have figured
out, I think the state machine dies if it is in a state and no event occurs.
If that is true, what will be an elegant way to "wait" inside a state till
some event occurs (i.e. keeping FSM alive)? 
I came up with 2 ways: 

1. Have following transition from the waiting state:
    Row < state_waiting , none, state_waiting , none, none>
and keep on calling process_event(none())
This however causes the entering the state again and again and gives me
segmentation fault ultimately.

2. Have following transition: 
  Row < state_waiting, none, state_waiting, none, Gc_always_false>
where guard condition Gc_always_false returns false, prohibiting the
transition but still keeping the state machine alive. 

Can you please tell me if the 2nd option is correct and if there is a better
way to sit idle in one state and keep the machine alive. 

Thanks! 

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