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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: GNAT for MS Visual Studio
Newsgroups: comp.lang.ada
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Date: Sun, 7 Oct 2007 09:49:21 +0200
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Date: 2007-10-07T09:49:25+02:00
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On Sun, 07 Oct 2007 09:21:40 +0200, Pascal Obry wrote:

> Now maybe some operations could be made safe, like those not using
> cursors. For example, in Ada.Containers.Vectors:
> 
>    function Element
>      (Container : Vector;
>       Index     : Index_Type) return Element_Type;
> 
> Why this could not be made safe ?

It can, but it is useless as long this safety is not expressed by the
contract of Vector. So the choices are:

1. to make all operations safe
2. to declare a safe subtype of Vector with only safe operations available
3. to introduce the notion of "safe operation" and to declare Element "safe
operation," using a pragma.

Neither works. 1) is distributed overhead, 2) is impossible due to the
language limitations, 3) is a mess [and possibly distributed overhead].

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