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From: Natasha Kerensikova <lithiumcat@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Reference counting and idempotent finalize
Date: Thu, 12 Sep 2013 04:53:39 +0000 (UTC)
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Date: 2013-09-12T04:53:39+00:00
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On 2013-09-11, Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
> On Wed, 11 Sep 2013 10:45:37 +0000 (UTC), Natasha Kerensikova wrote:
>
>>    procedure Release (Access_Value : in out Access_To_Actual_Data) is
>>    begin
>>       if Access_Value /= null then
>>         Access_Value.all.Counter := Access_Value.all.Counter - 1;
>
> A minor stylistic issue, you don't need .all in order to access components:
>
>            Access_Value.Counter := Access_Value.Counter - 1;
>

I thought addressing it explicitly in the OP would spare me from the
remark.

Even though I don't need .all, and usually skip when not needed, there
are situations like this reference-counting code when I feel the
confusion between objects and accesses to objects is too easy and harms
readability (at least when the reader is me).

The null comparison on the previous line is not enough to recognize at a
glance that Access_Value is indeed an access value, so I knowingly wrote
the optional explicit dereferencing here.

Now I might be a bit biased by my C background, the implicit
dereferencing in Ada feels a lot like the implicit conversion from array
to pointer-to-the-first-element, and from function pointer to function.