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From: dewar@cs.nyu.edu (Robert Dewar)
Subject: Re: Gripe about Ada, rep specs that won't.
Date: 1996/03/21
Message-ID: <dewar.827466868@schonberg>#1/1
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references: <00001a73+00002504@msn.com> <3146E324.5C1E@lfwc.lockheed.com>
 <4i98gg$8n1@solutions.solon.com> <Do9tMv.2p3@world.std.com>
 <4ia41k$e04@solutions.solon.com> <4ik5ip$cl6@watnews1.watson.ibm.com>
 <4iq71v$cvr@news4.digex.net> <dewar.827374356@schonberg>
 <4isol4$dm7@ra.nrl.navy.mil>
organization: Courant Institute of Mathematical Sciences
newsgroups: comp.lang.ada
Date: 1996-03-21T00:00:00+00:00
List-Id: <comp.lang.ada>

"Well, that's quite a nice bit of high-road preaching from behind your
dais up there :-), but Ada does NOT protect you from those holes.
Regardless of the value of the discriminant, you can still access ANY
of the fields in a variant record.  In fact, if I could rely on something
like Constraint_Error in those cases, I'd probably begrudgingly accept
the variant records of Ada.  As it stands now, though, it just gets in
my way without providing any protection: I cannot set the discriminant,
and yet I can access another discriminant's fields."

Of course you should get a constraint error if you access a field n the
variant that does not correspond to the current discriminant value. If
you find a case where this is not so, it is a bug, a significant one!
Report it as such. The whole point of the discriminant check is to
ensure this.