Article

From:
To:
Raoul De Kezel
Subject:
Re: Exceptions vs Error codes
Newsgroup:
borland.public.delphi.objectpascal

Re: Exceptions vs Error codes

In article <✉forums.inprise.com>
	Raoul De Kezel <✉hotmail.com> wrote:

> > Also, an important point in this article
> > is that free propagation of exceptions
> > across the call stack is a threat to
> > program stability unless you are able to
> > recover states in your intermediate
> > objects (or your objects are stateless).
> 
> Soooo true, and one of the reasons to prefer error codes.

It isn't very difficult in Object Pascal with correct use of
try..finally.

> In 1989, it was already well known how important it
> is to automatically put the system back in a consistent 
> state when propagating exceptions. And more than a decade 
> later most mainstream langages dont support this (and
> dont support well a formal specification of anticipated 
> exceptions, for that matter)

Specification of anticipated exceptions is a misguided dead-end.

> I used to program databases, which *do* automatically 
> restore system state when an exception is propagated.
> When I see a database exception, I am 110% sure that
> the system is in a consistent state. When I see a
> Pascal exception, I pray...

If the programmer is worth their salt and aware of exception safety,
they should be able to do it without much difficulty.

> > The same cannot be said of error codes
> > since they do not automatically
> > propagate.
> 
> Sure. Error codes have a visibility that exceptions
> dont have. That helps to prove correctness of propagation
> or handling, and I certainly understand that people
> working on critical software prefer error codes (in
> languages without automated rollback)

Unfortunately, error codes can make code all but unreadable.

-- Barry
--   If you're not part of the solution, you're part of the precipitate. Team JEDI: http://www.delphi-jedi.org NNQ - Quoting Style in Newsgroup Postings   http://web.infoave.net/~dcalhoun/nnq/nquote.html
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Originally created by
Tamarack Associates
Tue, 07 Feb 2023 05:04:19 UTC
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