Re: Self pointer in limited record

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 03 Sep 2007 17:55:33 +0200, Jean-Pierre Rosen wrote:

> Dmitry A. Kazakov a �crit :
>> It is difficult to see how an abstract state machine is not a type. The
>> very word abstract assumes generalization, reuse and instances. It is types
>> and generics, the tools to express the idea of instances.
>> 
> Sorry, but I beg to disagree here.
> 
> Abstraction is about the reduction of a real world objet to those 
> elements that are relevant for a given point of view.

Of just one object? I think that an abstraction always apply to a set of
things. What could be an abstraction of Spike, the dog?

> A singleton is an abstraction of a single object, and does not need a 
> type. I don't see anything in the word abstract that assumes generalization.

There is little abstraction in being alone. This is actually the reason why
no type is need for a singleton: no abstraction, no instances, no type.

In my view an abstract state machine has nothing to do with singletons. A
state machine might be a singleton, per chance. But an *abstract* state
machine is definitely a type that generalizes many concrete state machines.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de