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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to 'cross the chasm'?
Date: Fri, 11 May 2018 17:39:09 -0500
Organization: JSA Research & Innovation
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Xref: reader02.eternal-september.org comp.lang.ada:52303
Date: 2018-05-11T17:39:09-05:00
List-Id: <comp.lang.ada>

Niklas Holsti" <niklas.holsti@tidorum.invalid> wrote in message
news:flkvhfF1m7fU1@mid.individual.net...
> On 18-05-10 01:05 , Randy Brukardt wrote:
>> "Niklas Holsti" <niklas.holsti@tidorum.invalid> wrote in message
>> news:flegbrFj0qjU1@mid.individual.net...
>>> On 18-05-04 01:27 , Randy Brukardt wrote:
>>>
>>>   [snip]
>>>
>>>> There is no realistic chance that Ada will
>>>> ever be changed enough to make it amenable to GC.
>
>    [snip]
>
>> If one uses the canonical linked-list
>> implementation of finalization, objects with controlled parts remain
>> reachable until the appropriate master goes away -- so nothing gets
>> collected. (And a similar effect is necessary regardless of how
>> finalization
>> is implemented.) There still can be an underlying GC and it can be used
>> just
>> fine -- no one said anything about it actually be able to collect much.
>
> Can one summarize the effect of the current Ada rules as follows:
>
> - for dynamically allocated objects that do not need finalization, a GC
> implementation could release them when they become unreachable, just as in
> other languages,
>
> - for objects that do need finalization, a GC implementation would have to
> delay releasing the objects until their types go out of scope, which in
> most cases would not happen before the program is about to terminate?
>
> If so, the conclusion is that GC is becoming ineffective for Ada, because
> Ada programming style is changing to make more use of controlled types and
> finalization.

Correct, this is a perfect summary. Perhaps it should be clarified that
these are all objects designated by some access type, but of course you 
don't
need any way to deallocate local objects - they go away for free.

                 Randy.