From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,8b8748382fcfacc1
X-Google-Attributes: gid103376,public
From: "John J. Rusnak" <john.rusnak@mindspring.com>
Subject: Re: friend classes in ada95
Date: 2000/04/14
Message-ID: <38F7BC00.F88AD37E@mindspring.com>#1/1
X-Deja-AN: 611347104
Content-Transfer-Encoding: 7bit
References: <38F6B617.34E216A7@emw.ericsson.se>
X-Accept-Language: en
X-Server-Date: 15 Apr 2000 00:52:42 GMT
Content-Type: text/plain; charset=us-ascii
Organization: MindSpring Enterprises
Mime-Version: 1.0
Newsgroups: comp.lang.ada
Date: 2000-04-15T00:52:42+00:00
List-Id: <comp.lang.ada>

Stefan Folkesson wrote:

> In ADA95, is there a way to make the private part of one class
> accessable from another (see friend classes in C++)?
>
> The reason I wonder this is because I want to apply the 'Iterator
> Pattern' in my design. This demands that the Iterator object can access
> the attributes of the Aggregate object.
>
> Is this possible? Is there a pragma to supress the access check or do I
> have to declare the attributes of the Aggregate class in the public part
> of the specification.
>
> /Stefan

Yes, and no pragma is needed.

In fact,  a class has no control (that I am aware of) of who its "friends"
are.  The way to implement a friend relationship is to use a child
package.  A child package automatically has visibility into the private
parts of its parent's spec.  The implementation of a friend class through a
child package does involve a tighter coupling of the class and its
"friend", but this is a good thing.  One should only implement a friend
relationship if there is a strong need (and a need for strong coupling
between the classes).

-John