From: Brian Drummond <brian@shapes.demon.co.uk>
Subject: Re: Why is the destructor called multiple times after I declare an object?
Date: Mon, 11 Jan 2016 16:29:44 -0000 (UTC)
Date: 2016-01-11T16:29:44+00:00 [thread overview]
Message-ID: <n70l9o$ecn$3@dont-email.me> (raw)
In-Reply-To: n6v39b$efq$1@dont-email.me
On Sun, 10 Jan 2016 19:18:53 -0700, Jeffrey R. Carter wrote:
> On 01/10/2016 06:37 PM, Andrew Shvets wrote:
>>
>> Why is "Resetting values of Creat to defaults." displaying 6 times as
>> opposed to just twice?
>
> ARM 7.6(13-17.1) apply here. Note that Init declares a local variable of
> the type, which is finalized when Init returns, and that the anonymous
> object that is the result of the call to Init is finalized after
> initialization is finished.
> This gives you 2 calls to Finalize for each variable of the type
> declared and initialized by a call to Init. Finally you have a call to
> Finalize for each variable of the type when the program ends.
>
> http://www.adaic.org/resources/add_content/standards/12rm/html/
RM-7-6.html
Interesting. I thought you could eliminate one of those local copies
using "extended return" in the Init function, as in:
function Init return Creature is
begin
return TempCreature : Creature do
TempCreature.Name :=
Ada.Strings.Unbounded.To_Unbounded_String("dog");
TempCreature.Legs := 4;
TempCreature.WeightInGrams := 3000;
TempCreature.HeightInCm := 40;
end return;
end Init;
Somehow I expected "extended return" to allocate space and "build in
place" during the execution of the return statement.
Is this something legal that Gnat doesn't take advantage of? Or is there
a Gnat option I'm not aware of?
Of course instead of a default constructor, the record can be populated
with default values, to eliminate both the "Init" call and two temporary
objects, but the "problem" remains for the other constructor.
-- Brian
next prev parent reply other threads:[~2016-01-11 16:29 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-11 1:37 Why is the destructor called multiple times after I declare an object? Andrew Shvets
2016-01-11 2:18 ` Jeffrey R. Carter
2016-01-11 3:35 ` Andrew Shvets
2016-01-11 17:02 ` Brian Drummond
2016-01-11 16:29 ` Brian Drummond [this message]
2016-01-11 17:20 ` Simon Wright
2016-01-11 18:17 ` Bob Duff
2016-01-11 21:10 ` Dmitry A. Kazakov
2016-01-11 23:44 ` Randy Brukardt
2016-01-12 9:33 ` Dmitry A. Kazakov
2016-01-12 20:21 ` Randy Brukardt
2016-01-12 21:05 ` Dmitry A. Kazakov
2016-01-13 0:02 ` Robert A Duff
2016-01-13 8:31 ` Dmitry A. Kazakov
2016-01-13 9:01 ` Georg Bauhaus
2016-01-13 14:45 ` J-P. Rosen
2016-01-13 20:09 ` Dmitry A. Kazakov
2016-01-14 9:04 ` J-P. Rosen
2016-01-14 9:47 ` Dmitry A. Kazakov
2016-01-13 16:03 ` Robert A Duff
2016-01-13 19:59 ` Dmitry A. Kazakov
2016-01-14 10:04 ` Georg Bauhaus
2016-01-14 13:42 ` Dmitry A. Kazakov
2016-01-12 12:41 ` Brian Drummond
2016-01-13 20:18 ` Jacob Sparre Andersen
2016-01-14 1:31 ` Robert A Duff
2016-01-12 0:43 ` Jeffrey R. Carter
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