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From: Kilgallen@SpamCop.net (Larry Kilgallen)
Newsgroups: comp.lang.ada
Subject: Re: Ada 200X
Date: 2 Jun 2003 06:22:49 -0500
Organization: LJK Software
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 <3EDAD07A.3010200@attbi.com>
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Date: 2003-06-02T06:22:49-05:00
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In article <3EDAD07A.3010200@attbi.com>, "Robert I. Eachus" <rieachus@attbi.com> writes:
> And838N@netscape.net wrote:
> 
>  > There was one other issue I came across when writing my first Linked
>  > list in Ada.  There is no "this" keyword.  It didn't take long for me
>  > to realize that a class in Ada is not at all like a class as I
>  > understand from college (C++, Java).  The "flavor" of an Ada was C
>  > struct like to me and required passing "my" instance as a parameter
>  > to a procedure of function in a package so that I could use "this".
> 
> The feature that you are looking for is called an access discriminant. 
> This allows an object to have a self reference, or more important, a 
> reference to the containing object.  Unfortunately access discriminants 
> usually break information hiding.

I am not the original poster, but the case where I find this troublesome
is trying to replace a method for a parent type with enhanced code to:

        1. Do something special

        2. Do whatever the method for the parent type would do

        3. Do something else special

The lack of a construct to specify "corresponding method of ancestor"
seems to me to be what breaks information hiding.