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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Q: Ada.Unchecked_Deallocation
Date: 1996/07/21
Message-ID: <DuwnGt.Bz2@world.std.com>#1/1
X-Deja-AN: 170595625
references: <31E5D4D1.11DB36E1@jinx.sckans.edu>
 <EACHUS.96Jul16153330@spectre.mitre.org> <dewar.837835087@schonberg>
 <ws9zq4un5ni.fsf@schonberg.cs.nyu.edu>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-07-21T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <ws9zq4un5ni.fsf@schonberg.cs.nyu.edu>,
Laurent Guerby <guerby@gnat.com> wrote:
>   type KLUNK_WITH_EMPTY_FINALIZE is new KLUNK with null record;
>   procedure Finalize (Obj : KLUNK) is
>   begin null; end Finalize;
>
>   And instead of applying the pragma, you declare objects of this new type.
>A smart compiler can optimize away calls to such a Finalize subprogram.

This would have to be a link-time optimization.

Instead, do it the other way around: Define the no-finalize version
first, and then derive the finalized version from that.  Then, the
compiler *can* tell (at compile time) that the first type has null
Finalize, since it doesn't override the known-null version inherited
from type Controlled.

Either way, you have to be careful, though.  You can't declare nested
objects of the no-finalize type, or you'll get a storage leak.  And what
if it's in a generic package, which is *sometimes* instantiated in a
nested place?

- Bob