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Newsgroups: comp.lang.ada
Subject: Re: Allocators and exceptions
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From: Stephen Leake <stephen_leake@stephe-leake.org>
Date: Wed, 12 Sep 2007 08:29:08 -0400
Message-ID: <utzq0kqy3.fsf@stephe-leake.org>
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Date: 2007-09-12T08:29:08-04:00
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Maciej Sobczak <see.my.homepage@gmail.com> writes:

> On 11 Wrz, 11:16, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
> wrote:
>
>> >>> P.S. Exceptions in constructors is a bad idea.
>>
>> > No, it's a very good idea. Otherwise you have to deal with half-baked
>> > objects, which is Even Bigger Mess (tm).
>>
>> This is what you get when the exception is propagated out of a constructor.
>
> In this case I want the constructor to be rolled back.
> Without exceptions (and rollback) the only option for handling errors
> in initialization of (sub)components is to leave them half-baked.

The point is that the constructor itself must do the roll-back, and
leave the object in a consistent state.

The rule should be:

    Constructors should not propagate exceptions up; they must handle
    all exceptions internally.

-- 
-- Stephe