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Re: What's so cool about Scheme?

Matt Hellige wrote:
> I suppose the poster was referring to what's usually called encapsulation,
> in that OO design practices encourage us to create objects that have
> some state, but that state is only mutable through a set of operations
> that the object chooses to expose. In this sense, these operations can
> enforce any invariants they'd like on the internal state of the object.

Then I would be interested in understanding how this is different from the
emphasis given to cohesion and coupling in structured programming.  If 
OO dosn't mean anything more than encapsulation then I suggest the term 
is meaningless, as an object becomes indistinguishable from an ADT.

My understanding of the term object is rather informal but roughly 
equates to:

"Objects are encapsulated state machines exchanging messages amongst 
themselves, and with a number of external 'worlds'."

Not suggesting this is anything authoritive, but it was arriving at this 
definition that finally allowed me to understand the concept of OO 


[1] Well at least I like to think I understand OOP ;).

Andrae Muys                       But can it generate *quantum* Haiku
<andrae.muys@braintree.com.au>    error messages, in Latin, where each
Engineer                          line of the error message is a
Braintree Communications          palindrome? -- Mike Vanier on perl