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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: A hole in Ada type safety
Newsgroups: comp.lang.ada
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Date: Sat, 7 May 2011 11:28:05 +0200
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Date: 2011-05-07T11:28:05+02:00
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On Sat, 07 May 2011 11:09:44 +0200, Florian Weimer wrote:

> Run-time complexity for reference counting is less than for full
> garbage collection.  Making it a language feature, rather than a
> library-provided functionality, makes it easier for implementations to
> optimize updating the counts.

Hmm, what about tasking? I gather that a built-in counter must be atomic.
Whether implemented lock-free or using a spin lock, that would be a
considerable overhead.

> As usual, there is a trade-off between
> flexibility and overhead: if the reference counters are kept separate,
> it is possible to implement weak pointers and safe references to
> sub-components.

Interesting. Do you have a certain schema in mind, how to this?

>> Type safety is not about detering malicious programmers, merely careless 
>> ones.
> 
> I think type safety is important for ending up with language semantics
> that can be explained.

I agree. It is the semantics which yields to safety, not the reverse.

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