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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Derived private interface
Date: Wed, 10 Aug 2011 16:56:00 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2011-08-10T16:56:00-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:1bs0xoar40rx.6yb23bgkfrew.dlg@40tude.net...
> On Tue, 9 Aug 2011 16:35:14 -0500, Randy Brukardt wrote:
>
>> I understand the value of the Open/Close principle, but it only is a win 
>> in
>> Ada if there are multiple interfaces associated with an object. 
>> Otherwise,
>> the amount of change is the same (or even less) for the non-OOP solution.
>
> It could be true only if there were only one place of dispatch.

That's exactly the case I meant.

> In reality
> there are many dispatching calls and many class-wide operations (for which
> there is no typed procedural equivalent).

Reality? The reality is in the web server interface I was describing there 
was only one such point of dispatch, and only a single interface to dispatch 
to. It's clearly a special case, but one that is pretty common in the 
systems I've worked on.

All I was saying is that in that special case, there is no value to OOP in 
Ada.

> Procedural solution would
> necessary have to bend design in order to reduce the number of such 
> places,
> each requiring maintenance.

Not necessarily; a lot of problems have obvious bottlenecks where everything 
goes through a single point. Making complex dispatching designs in such 
cases only increases complexity and difficulty of maintenance.

                                     Randy.