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From: Robb Nebbe <nebbe@iam.unibe.ch>
Subject: Re: Real OO
Date: 1996/04/04
Message-ID: <3163D21C.460E@iam.unibe.ch>#1/1
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references: <4jbmsk$uo5@watnews1.watson.ibm.com> <DpBIEE.L5u@assip.csasyd.oz>
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organization: Dept. of CS, University of Berne, Switzerland
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newsgroups: comp.lang.ada,comp.lang.eiffel,comp.object
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Date: 1996-04-04T00:00:00+00:00
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Don Harrison wrote:
 
> Conclusion:
> 
> Ada:
>   - more efficient, but
>   - manual optimisation places a burden on developer
>   - reduced flexibility/reusability
>   - syntactically complex
> 
> Eiffel:
>   - less efficient, but
>   - automatic optimisation means that the the efficiency gap is 
>     reduced as is the burden on developer
>   - greater flexibility/reusability
>   - syntactically simple
> 
> Don.

These conclusions are in direct conflict with my experience. My
experience is that was is basically going on in Ada is that the
programmer is allowed to make more of the semantics explict
rather than implicit. I get to tell the compiler things I already
know instead of having the compiler guess at them. I experience
no burden because of Ada's approach.

I also haven't found any real difference in flexibility or
reusability due to Ada's distinction between class-wide and
specific types. I do think that it helps a lot in understanding
someone else's code but this is really a consequence of having
more semantic information presented to me rather than having to
figure it out.

I don't think you have a sufficient understanding of the approach
taken by Ada yet. You seem to have most of the facts but you
don't seem to have synthesised it into a coherent whole. If you
understand the separation between interface and implementation
inheritance and adopt a programming style that makes heavy use
of abstract classes (this should sound a little like Sather)
then the distinction practically falls in your lap.


Robb Nebbe