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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Musing on defining attributes and the ability to define an
 "abstract type X"-interface.
Date: Mon, 7 Aug 2017 18:06:51 -0500
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Xref: news.eternal-september.org comp.lang.ada:47639
Date: 2017-08-07T18:06:51-05:00
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"Shark8" <onewingedshark@gmail.com> wrote in message 
news:e8fcbf71-7432-4410-bae7-34943479bf81@googlegroups.com...
...
>And this proposal is about adding the ability to extend to the whole 
>language
>without having to depend on (or be restricted to) tagged types.

Ada 9x originally allowed 'Class on all types. It eventually got dropped 
because it was a lot of mechanism and Ada 9x looked like it might be too 
complex for anyone to actually implement. (That was the infamous "scope 
reduction"; a few thigns were snunk back in after that - specifically 
finalization and library-level renaming - but most of the stuff stayed out. 
Some have reappeared in later versions of Ada.)

It's occassionally come up, but there hasn't been much interest in reviving 
it in general, because it doesn't buy a lot. If you disagree, please come up 
with examples of things are both important and hard to do with the current 
language.

                                      Randy.