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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Ada 95 visibility question
Date: 1997/09/26
Message-ID: <EH3FF3.6Ho@world.std.com>#1/1
X-Deja-AN: 275597539
References: <342A7989.219C@catalina-inter.net>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-09-26T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <342A7989.219C@catalina-inter.net>,
Chris Sparks (Mr. Ada) <mrada@CATALINA-INTER.NET> wrote:
>Wouldn't peek_a_boo be visible since the types are part of the "c" (no
>pun intended) hierarchy?

No.  It's not unreasonable to think that ought to be the case, but the
actual rules in the RM say otherwise.  As I said, it's a subtle issue.

You inherit from your parent, not your grandparent.  You inherit stuff
from your grandparent only because your parent inherited those things.
And your visibility on those things depends on your visibility of your
parent.  In this case, you know who your grandparent is, and you know it
has the Peek_A_Boo component, but you don't know *you* have that
component.  It's just a minor oddity caused by Ada's model of always
having an imaginary (implicit) declaration for these things, which
occurs (or is imagined to occur) in some well-defined place in the
program.

- Bob