Taxonomy of Facets & Composites

[Tyler Close]

I (Tyler) wrote:
> Markm wrote:
> > To recap the terminological points in this document:
> >
> > At the "laws of physics" level, there are only objects, not
> > facets or
> > composites.  An object is a combination of state and
> > behavior.  Using Norm's
> > note, I'd further say that the behavior computes new state
> > and outgoing
> > messages as a function of the current state and the
> > incoming message.  An
> > object reference refers to a given object.  An object only
> > has one object
> > reference.  (Or, all object references to the same object
> > are equivalent.)
>
> An elaboration of 'equivalent' should be included.
>
> All references to an object are 'equivalent' in that they
> refer to exactly the same thing and that that thing will
> respond in the same way to exactly the same set of messages
> for all references.
>
> An object may have many references that may or may not
> respond to an EQ message (ie: two references to the same
> object are equivalent, but the holder may have no way of
> knowing that they are equivalent). If the holder has access
> to the innards of the reference, those innards may differ
> between references to the same object.
>
> The validity of two references to the same object may
> change independently. (ie: one may become invalid while the
> other remains valid).

Once a reference becomes invalid, it remains invalid.

More wiggle room:

Equivalent references may use different communication protocols for
the delivery of messages to and from the referred to object. (ie: one
may push a message onto a CPU stack and another may send an HTTP POST,
but they are still equivalent).

Tyler


__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com