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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Overloading operator "=" for anonymous access types?
Date: Mon, 14 Jan 2019 17:08:32 -0600
Organization: JSA Research & Innovation
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Date: 2019-01-14T17:08:32-06:00
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<daicrkk@googlemail.com> wrote in message 
news:0c56d9f4-8861-4c74-b170-a973e3789b08@googlegroups.com...

>I second that. Access Cell is an access-to-object type whose designated
>type is Cell (check), Cell has a user-defined primitive equality operator
>(check) such that its result type is Boolean (check), it is declared
>immediately within the same declaration list as Cell (check), at least one
>of its operands is an access parameter with designated type Cell (both
>operands are, check).
>According to 4.5.2, universal_access "=" should never be allowed to kick in
>at all here, not even with "L = null". Or am I missing something?

Yup, I agree with this. My first thought when reading that example is that 
it is wrong, because I don't remember anywhere in Ada where the same 
operator with arguments of the same type means different things. I don't 
think the use of "null" could change that.

Dunno if John wrote that for a different version of Ada, or he was just 
confused by a rule that barely makes sense anyway.

As always, best avoid anonymous access types unless you have to use one of 
their special features (dynamic accessibility, dispatching, special 
discriminant accessibility, or closures [for access-to-subprograms]). And 
better still, lets lobby to get those special features optionally available 
for named access types so no one every has to use an anonymous anything. :-)

                                          Randy.