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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada Annoyances
Date: Thu, 29 Jun 2017 19:47:20 -0500
Organization: JSA Research & Innovation
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Xref: news.eternal-september.org comp.lang.ada:47199
Date: 2017-06-29T19:47:20-05:00
List-Id: <comp.lang.ada>

"Niklas Holsti" <niklas.holsti@tidorum.invalid> wrote in message 
news:erl137Fp39dU1@mid.individual.net...
> On 17-06-27 00:47 , Randy Brukardt wrote:
...
>> And changing the tag via assignment means having to be prepared to
>> change finalization of  objects after the fact as well. Ugh.
>
> Isn't finalization of local objects usually implemented by creating a list 
> of these objects, and then traversing that list on scope exit? It seems to 
> me that changing the tag of an object on the list should not be a problem; 
> the new tag would just lead to a different Finalize, through normal 
> dispatching.

That's not a problem. The case I was thinking about was one where the change 
in tag caused an object which was not previously controlled to become 
controlled. Then the object would have to be added to the finalization list, 
but not to the head, but rather to the exact point where the original object 
was declared. That would be very difficult.

I just spent most of the winter fixing a bug related to that for variant 
records in Janus/Ada, and this case would be worse (because there's no 
enclosing object in which to put helper components).

                                      Randy.
       .