From: Robert A Duff <bobduff@world.std.com>
Subject: Re: accesibility level problem
Date: 1999/03/01
Date: 1999-03-01T00:00:00+00:00 [thread overview]
Message-ID: <wccr9r99jge.fsf@world.std.com> (raw)
In-Reply-To: 7alc7m$uo2$1@nnrp1.dejanews.com
robert_dewar@my-dejanews.com writes:
>...It is our
> experience that talking about accessibility levels is
> not illuminating to the typical user, and the sections of
> the RM describing the accessibility rules are notoriously
> complex (ask Bob Duff's opinion, he was their author and
> I believe he has said he finds them hard to understand :-)
True. We totally rewrote that section several times during the language
design, with different terminology, desperately trying to make it both
correct in detail, and easy to understand. IMHO, we didn't succeed in
the second part, and I don't know how to do better.
So I agree with Robert that the compiler should say something vague
about the underlying rationale. You've *got* to understand that
rationale in order to program in Ada or C or anything similar!
I think the original poster wondered why it was all based on the access
type, and not on the object. The problem is that the object declaration
doesn't contain any information about where the thing points, and we
didn't want to do it all with run-time checks (although Tucker invented
access parameters fairly late in the game, and they allow a limited form
of run-time checking).
- Bob
--
Change robert to bob to get my real email address. Sorry.
next prev parent reply other threads:[~1999-03-01 0:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-02-19 0:00 accesibility level problem Thomas Handler
1999-02-19 0:00 ` steve quinlan
1999-02-20 0:00 ` robert_dewar
1999-02-20 0:00 ` Steve Quinlan
1999-02-21 0:00 ` robert_dewar
1999-03-01 0:00 ` Robert A Duff [this message]
1999-03-02 0:00 ` Thomas Handler
1999-02-21 0:00 ` Thomas Handler
1999-02-21 0:00 ` Steve Quinlan
1999-02-22 0:00 ` robert_dewar
1999-02-22 0:00 ` robert_dewar
1999-02-22 0:00 ` Thomas Handler
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