Re: [boost] Re: i/o state savers exception-safety

From: Thomas Witt (witt_at_[hidden])
Date: 2002-08-02 09:54:23

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Friday 02 August 2002 16:01, David Abrahams wrote:
> From: "Thomas Witt" <witt_at_[hidden]>
>
> Eating the exception is a viable approach on any of these platforms, and
> may be preferable to termination when uncaught_exception is unavailable.

This might created a false sense of safety. In order to have the same 
behaviour as on platforms that have uncaught_exception(),  you will need 
something like the following to "restore" the exception.

pseudo-code untested.

void gunc(ostream& out)
{
  // Make sure io_state_saver dtor is called before we
  // try to restore io exceptions.
  {
    io_state_saver s(out);

    // Do smth.

  }
  // trigger an exception if the state_saver ate it even if no
  // stack unwinding ocurred.
  out.clear(out.rdstate());
}

I think that this is clumsy enough to not use this approach for platforms 
where uncaught_exception is available, but it is easily forgotton on those 
platforms where uncaught_exception is not available.

> However, a library author must take
> responsibility for the consequences of his code. The hard work must be
> done.

Violent agreement.

- --Thomas

- -- 
Dipl.-Ing. Thomas Witt
Institut fuer Verkehrswesen, Eisenbahnbau und -betrieb, Universitaet Hannover
voice: [phone] - 4273, fax: [phone]
http://www.ive.uni-hannover.de
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

iD8DBQE9Sp0i0ds/gS3XsBoRAtUaAJ9ANFhp8pLbSTwfGSgPi//AUJpM8wCfVwGu
kNCVhnpjiEQZeCXDxs3DW3E=
=xvyx
-----END PGP SIGNATURE-----