Re: [Boost-users] statechart null in_state_reaction

From: Andreas Huber (ahd6974-spamboostorgtrap_at_[hidden])
Date: 2007-12-19 18:02:18

Hi Sean

> I would like to implement a null-op in_state_reaction - The
> in_state_reaction template requires a action argument whereas the
> transition to self doesn't

It's kind of an oversight that in_state_reaction does not define defaults 
for its last two template parameters. I'll change that for 1.36 
(unfortunately no new functionality can go in 1.35).

Usually, a state_machine can ignore an event simply by not defining a 
reaction for it, which is also the reason why in_state_reaction currently 
requires a function to execute. However, all ignored events will be handed 
to state_machine<>::unconsumed_event, which sometimes is not what you want.

> Which is the preferred method ?

Since transition to self will always exit and reenter the state, the only 
correct way is with in_state_reaction.

HTH,

-- 
Andreas Huber
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