Re: How does one model behavior?

From: David Cressey <>
Date: Wed, 09 Apr 2008 15:00:20 GMT
Message-ID: <8S4Lj.14566$lt2.5783_at_trndny05>

"Leslie Sanford" <> wrote in message news:47fcd175$0$11371$
> "David Cressey" wrote:
> > "Dmitry A. Kazakov" wrote:
> >> David Cressey wrote:
> >>
> >> > How does one model behavior?
> >>
> >> Behavior of what? Of the program, of a physical system?
> >>
> >> > It would seem to me that, since conveying behavior from one object to
> >> > another rests on messages, and since messages are made of data,
> >> > one needs a data model for the messaging system before one begins to
> >> > come up with a bhavior model for a system of collaborating objects.
> <snip>
> >> To your point about messages parameters.
> >
> > I didn't mention parameters. I don't know what you mean.
> As I understand it, sending an object a message at the code level means
> invoking one of its methods. A method takes zero to many parameters, or
> arguments. When you say that messages are made up of data, my point of
> translates that to meaning the arguments passed to methods, i.e. the
> arguments are the data. Perhaps that's the impression Dimitry got as well.

I'm not really asking at the code level. I think a message specifies an operator, not a method.
The relation between operator, class, and method has to be managed somewhere. At the code level, you are probably right.

> Further, when you say "that one needs a data model for the messaging
> before one begins to come up with a behavior model for a system of
> collaborating objects," I translate that to mean that one should "model"
> data passed between objects via their methods first before modeling how
> objects respond/behave to messages (method invocations). Which is fine, I
> guess, but usually when designing a class I decide what it needs to do,
> this goes hand in hand with what it needs to know in order to do it. To me
> it's like working with algorithms (or behavior) and data structures (or
> data). I can't say if one comes before the other.
> Could be my head is stuck at the code level which is where I mainly live
> I don't understand what it is you're asking. In which case, I welcome
> enlightenment/clarification.
Sorry. I don't know enough OO to provide enlightenment. I understand data pretty well.

Perhaps you could tell me how you express "what a class has to do". This might be close to what I'm asking for when I say "how to you model behavior". Received on Wed Apr 09 2008 - 17:00:20 CEST

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