From: Martin von Loewis <loewis@informatik.hu-berlin.de>
To: <rysio@rumcajs.chemie.uni-halle.de>
Cc: egcs-bugs@cygnus.com, egcs@cygnus.com
Subject: Re: Troubles with exception specification
Date: Thu, 05 Nov 1998 05:10:00 -0000 [thread overview]
Message-ID: <199811050926.KAA09474@pandora> (raw)
In-Reply-To: <Pine.LNX.3.96.980922104403.5699A-100000@rumcajs.chemie.uni-halle.de>
>> 2. The call of B::func should throw `bad_exception', but it doesn't!
Thanks for your bug report. After closer inspection, and several
discussions, this is what I found:
In section 14.6.3 of "The C++ programming language", Stroustrup
explains that adding bad_exception to the exception specification will
activate the "exception mapping", which means that exceptions not
listed in the specification will be mapped to bad_exception by the
implementation.
In section 15.5.2 of the C++ Standard, paragraph 2 explains that such
mapping is performed only if unexpected throws or rethrows, which it
doesn't do by default (18.6.6.2).
Mr Stroustrup confirms that this is a contradiction between his book
and the adopted standard. He maintains that the standard should have
specified such exception mapping, and has brought this issue before
the standards committee
( http://www.research.att.com/~bs/3rd_issues.html ).
egcs currently implements the standards behaviour and not Stroustrup's
description. I'd propose that this is remains unchanged until a
decision is made by ISO.
Please note that you can work-around this discrepancy. Just define an
unexpected_handler:
#include <exception>
void my_unexpected()
{
throw std::bad_exception();
}
int main()
{
std::set_unexpected(my_unexpected);
//more code
}
Hope this helps,
Martin
P.S. Even though this came up the first time, I propose to add it to
the FAQ ("Why does bad_exception not work?") or as a non-bug to the
"Known bugs list".
next prev parent reply other threads:[~1998-11-05 5:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-09-22 5:33 Ryszard Kabatek
1998-11-05 5:10 ` Martin von Loewis [this message]
1998-11-06 4:27 ` FAQ vs Known Bugs List vs .texi Docs Gerald Pfeifer
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