Re: [boost] [msm] eUML guard/action location

Subject: Re: [boost] [msm] eUML guard/action location
From: Darryl Green (darryl.green_at_[hidden])
Date: 2009-12-14 09:30:51

On Mon, 2009-12-14 at 13:31 +0100, Christophe Henry wrote:
> >Are all those parentheses used for optional arguments, or could we consider eliminating them?
> 
> I'd love to eliminate them but don't see how. They actually are constructors.
> The complete expression would be something like:
> 
> typedef BOOST_TYPEOF(build_stt((
> DestState() = CurrentState() + cool_event()[guard()]/action(),
> DestState2() = CurrentState() + cool_event()[guard2()]/action2()
> ) ) ) transition_table;
> 
> So I'm really just pretending to pass on-the-fly instances of
> arguments from types DestState, CurrentState, etc. to evaluate the
> result with typeof after proto is done.

Yes it is an interesting "hack".How "pretend" have you been able to make
this?

I was actually thinking about exactly this today (long drive - actually
- correction - I was thinking about it yesterday - it's now early
morning here) and wondering what the consequences were. Does it result
in actually default constructing all these (temporary) objects? Won't
that be expensive and/or have undesirable side effects?