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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Prefixed notation for non tagged types
Date: Mon, 18 Dec 2017 16:31:06 -0600
Organization: JSA Research & Innovation
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Date: 2017-12-18T16:31:06-06:00
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"Simon Wright" <simon@pushface.org> wrote in message 
news:lyzi6hfl6r.fsf@pushface.org...
...
> Naturally, I wasn't involved in any ARG discussions about this (not
> being a member!), but I'd have thought the ideal would be for any
> derived type (which includes private types, I think?) to be a candidate.

My recollection was that the original idea was to allow it for any type, but 
that ran into problems with access types. Then we considered allowing it for 
any composite type, but that ran into problems with private types (which can 
be completed with an elementary type, specifically an access type). 
Requiring "tagged" side-stepped the problems, and it seemed like a better 
solution than adopting something that has known problems (which, once 
adopted, we're stuck with forever).

I think we would have been better off getting rid of the implicit 'Access in 
the prefixed notation (no other Ada feature does that); in that case, there 
wouldn't have been a problem with any type. That suggestion went nowhere, 
though.

                                 Randy.