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From: Matthew Heaney <mheaney@on2.com>
Newsgroups: comp.lang.ada
Subject: Re: memory management in Ada: tedious without GC?
Date: Mon, 19 May 2008 08:37:11 -0700 (PDT)
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Xref: g2news1.google.com comp.lang.ada:244
Date: 2008-05-19T08:37:11-07:00
List-Id: <comp.lang.ada>

On May 19, 4:39=A0am, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
>
> I've found two differences:
> 1. No support for exception-safe assignment in Ada.

It depends on how you define "exception-safe".  Assignment in Ada
makes only a "basic guarantee" wrt exception safety; that is, state is
not preserved but invariants are preserved. (State is not preserved
because finalization of the LHS happens before the assignment proper.)

Here's a helpful article that defines "basic" vs. "strong" vs. "no-
throw" guarantees:

http://www.boost.org/community/exception_safety.html


> 2. Memory leak after exception is raised while initializing the
> allocated object in Ada.

If by "initializing" you mean invoking a controlled action
(Initialize), then you'd get Propgram_Error, which means you have a
broken program anyway.

I do forget the exact rules about memory reclaimation, though; if I do
this:

declare
  P : T_Access :=3D new T;
begin

and the initialization of the object designed by P fails (e.g. because
controlled initialization fails, which raises Program_Error, or
because component initialization fails, which raises
Constraint_Error), then what does the language say about reclaiming
the memory allocated for P.all?  Good question...