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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: discriminant questions
Date: Wed, 21 Sep 2011 10:08:15 +0200
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Date: 2011-09-21T10:08:15+02:00
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On Tue, 20 Sep 2011 16:28:55 -0700 (PDT), ytomino wrote:

> (To avoid confusion, I do not use names of "Get" and "Set".)
> 
> function Element (C : Container) return Element_Type;
> function Set_Element (C : Container; New_Item : Element_Type);
> 
> These functions may copy Element_Type.
> It's futile cost if Element_Type'Size is large.

If you want referential semantics that must be specified explicitly. I
prefer to use containers of smart pointers for such purposes.

Otherwise, I bet that a controlled accessor object would cost a lot more
than copying for almost all elements. Controlled types are very expensive.

Quite often copying (by-value semantics) is even desired when dealing with
concurrency issues.

It was one of key advantages of Ada 83 which tried to stay reference vs.
value agnostic. It is sad to see, started with Ada 95, the drift towards
IMO wrong direction under the influence of Java et al.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de