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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Building limited types through nested creator functions
Date: Tue, 7 Feb 2012 14:25:40 +0100
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Date: 2012-02-07T14:25:40+01:00
List-Id: <comp.lang.ada>

On Tue, 07 Feb 2012 11:58:01 +0100, Georg Bauhaus wrote:

> On 07.02.12 10:10, Dmitry A. Kazakov wrote:
> 
>> The problem is that constructing functions of Ada are no replacement to
>> constructors, especially not with limited types.
> 
> Won't constructors have the same issue with limited private types
> and no copying?

The problem is specific to functions. A function returns a newly created
object, fully operational with all bells and whistles. This contradicts to:

1. limited types (non-copyable)
2. abstract types (no instances)
3. information hiding and partially operational objects

Constructor copies nothing. It is never called explicitly. No need to worry
about visibility issues. It does not promise or expose things which never
should come into existence (like creation of an abstract object). It does
not allocate memory, so it is much easier to roll back. It is much simpler
and, for all, a sound model which cannot be properly annotated with types.

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