From: Ray Blaak <blaak@infomatch.com>
Subject: Re: package dependence question
Date: 2000/05/30
Date: 2000-05-30T00:00:00+00:00 [thread overview]
Message-ID: <uk8gb3hvg.fsf@infomatch.com> (raw)
In-Reply-To: wccog5o809g.fsf@world.std.com
Robert A Duff <bobduff@world.std.com> writes:
> One thing you can do is declare tagged type Node, and then "type
> Node_Ptr is access all Node'Class;". Make types A, B, and C derive from
> Node. Then B can have a component like "Parent: Node_Ptr;". You lose
> type checking -- the parent of a B is always an A, but the code doesn't
> say so, except in a comment.
Put the Parent : Node_Ptr in the Node type. Full type checking can be achieved
by making the constructors for a B node require an A node as a parent
parameter (and in general, a arbitrary node's constructor has a signature in
terms of the required parent node). Safety by construction!
--
Cheers, The Rhythm is around me,
The Rhythm has control.
Ray Blaak The Rhythm is inside me,
blaak@infomatch.com The Rhythm has my soul.
next prev parent reply other threads:[~2000-05-30 0:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-05-29 0:00 package dependence question Carl Banks
2000-05-29 0:00 ` Robert Dewar
2000-05-29 0:00 ` Jeff Carter
2000-05-29 0:00 ` Ray Blaak
2000-05-29 0:00 ` Antonio Dur�n Dom�nguez
2000-06-03 0:00 ` Robert I. Eachus
2000-05-30 0:00 ` Robert A Duff
2000-05-30 0:00 ` Ray Blaak [this message]
2000-05-30 0:00 ` Brian Rogoff
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