Re: [Boost-users] [statechart] Can events carry data?

From: BRIDGES Dick (Dick.Bridges_at_[hidden])
Date: 2005-08-31 15:34:44

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] 
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Peter Petrov
> Sent: Tuesday, August 30, 2005 1:13 PM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] [statechart] Can events carry data?
> 
> 
> BRIDGES Dick wrote:
> > Is there any provision for "event-local" storage?  I'd like 
> to create
> > events that carry data (e.g., timestamp, source, etc.) to be used by
> > reactions and transitions to update state-local storage.
> > 
> > I didn't see anything like this in the documentation.  Bad 
> idea?  Major
> > drawbacks?  If it wouldn't be a problem, how might I go 
> about doing it?
> 
> 
> struct MyEvent : public boost::statechart::event<MyEvent>
> {
>     int myData;
>     double myOtherData;
>     MyClass myOtherOtherData;
> };
> 
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Thank you for the example.  

I'm still not clear on the requirements surrounding such an
instance.  For example, the reference requires that
<code>new E(*pCE)</code> be well-formed and make "a copy of
pE".  Does the current implementation work ok with 
boost::shared_ptr?  How about auto_ptr?  If a data member
would normally require a deep copy, would I be better off
managing it external to the event object - or avoiding that
type of data altogether?  How many copies are we talking
about here?

Any cautions and/or advise regarding the use of data members
in events would be appreciated.

Thanks again for the response.

Regards,
Dick Bridges