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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Adding "()" operator to Ada 200X
Date: Tue, 3 Jun 2003 15:24:30 -0500
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Date: 2003-06-03T15:24:30-05:00
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Frank J. Lhota wrote in message ...
>"Matthew Heaney" <mheaney@on2.com> wrote in message
>news:1ec946d1.0306021542.58714996@posting.google.com...
>> If you're going to make a change in the syntax of the language, then
>> it has be because it allows you to do something you can't do already.
>> For example, there's no way to declare an access subtype right now
>> that means "all the access values except null."  A useful language
>> change would be to allow the declaration:
>>
>>   type Element_Access_Base is access all Element_Type;
>>
>>   subtype Element_Access is Element_Access_Base range not null;
>
>This is an interesting idea, and we should probably pursue it further
in
>another. Constraint checking has always been tremendously helpful.
There is
>one potential (but not insurmountable) problem with this proposal: in
the
>absence of explicit initializations, an access variable is initialized
to
>null.


Already done. See AI-00231. (But there are some problems with doubly
constrained subtypes, so it is not yet finished.)

         Randy.