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From: Tucker Taft <stt@averstar.com>
Subject: Re: Another important feature of Ada
Date: 2000/11/15
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Date: 2000-11-15T16:37:26+00:00
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I also believe strongly in the value of separating interface and implementation.

Whenever I discuss this issue, I generally fall back on the analogy of
a legal contract, where it would be frightening to have to ask the company working
for you to give you "today's contract," which they will extract from
the current work in progress.  

This is essentially the story in Java and Eiffel with classes, 
where there is no separate spec, but you can
extract the "contract" from the implementation.  Of course, Java has
"interfaces" and Eiffel has "deferred classes," but there is a lot of
code which is not just implementing one of these, and all of that
code has no physically separate "contract" defining what it does.

Not cool in my view.

>From anecdotal experience, the fact that Ada has separate package specs
is very helpful in getting developers to focus on the notion of an
interface.  With Java, that seems to be getting lost again.

-Tucker Taft  stt@averstar.com