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

Subject: Re: [boost] [msm] eUML guard/action location
From: Christophe Henry (christophe.j.henry_at_[hidden])
Date: 2009-12-14 09:45:37

>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?

This is actually what I find so cool with the typeof feature (is it
too late to donate a kidney for it? ;-) ).
We are calling constructors and lots of operators and it costs nothing
run-time because typeof only evaluate the return value of
build_stt(...).
So no call actually happens. All what you have really is a typedef.
The only side effect (besides compiler support) is that you need an
empty constructor or would be forced to pass some dummy value.