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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to ?cross the chasm??
Date: Mon, 7 May 2018 09:25:34 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:52064
Date: 2018-05-07T09:25:34+02:00
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On 07/05/2018 03:31, Paul Rubin wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>> This is easily done in present Ada using handles to a
>> reference-counted objects.
> 
> That's not much different from gc from the user's perspective, other
> than problems handling cycles.

Cycles are easily avoidable too by separating target objects and 
handles. All target objects types go into the private part of the 
package. When only handles are visible there is no way the end user 
could construct a cycle.

The difference to GC is determinism and efficiency. You don't need to 
lock in order to decide if the object must be reclaimed.

If the overhead and non-determinism of GC is OK, then of course there 
would be no problem with adding detection of cycles in reference counted 
object. I did that for an implementation of graphs, not a big deal at all.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de