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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Ada tagged types not as powerful as C++ for dispatching???
Date: 1997/08/18
Message-ID: <EF38JJ.MF@world.std.com>#1/1
X-Deja-AN: 264908134
References: <33F4D31F.6E511B93@mci.com>
 <JSA.97Aug16191349@alexandria.organon.com>
 <01bcab6a$f2061820$92165da6@csp3610x>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-08-18T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <01bcab6a$f2061820$92165da6@csp3610x>,
Troy Noble <tmnoble@rmi.net> wrote:
>The only difference between what you tried and what I tried
>is that in my message on this newsgroup I put the definition
>of Circle_Ptr INSIDE package Figures.  In my non-working
>code I had defined Circle_Ptr INSIDE my procedure
>Test_Figures.

That explains it.  You can't convert from a more-nested access type to a
less-nested one, because that could create dangling pointers.  (There
are ways to do it -- e.g. using Unchecked_Access, but it's usually best
to just put the access types at library level.)

>Do you think this is a bug in GNAT that I should report,
>or was it in fact detecting the error properly?

GNAT is correct to complain.

- Bob