Re: assignment operator implementation

From:
David Abrahams <dave@boost-consulting.com>
Newsgroups:
comp.lang.c++.moderated
Date:
11 Nov 2006 03:39:02 -0500
Message-ID:
<87ac2yhge3.fsf@pereiro.luannocracy.com>
"Andrei Alexandrescu (See Website For Email)"
<SeeWebsiteForEmail@erdani.org> writes:

David Abrahams wrote:

"Andrei Alexandrescu (See Website For Email)"
<SeeWebsiteForEmail@erdani.org> writes:

Exception safety has a price, no doubt about it.


No, it doesn't! The C++ standard library exception-safety
specification imposes no overhead in principle over the earlier
version that specified undefined behavior if user-supplied operations
threw.


I meant something different but was hasty:


Okay; if you understand it already, please be more careful to say what
you mean. People have way too many misconceptions about this without
help from the influential-but-hasty.

1. If you aim for "higher" exception safety you incur more costs;
that's a spec issue.

2. If you implement an assignment with copy-and-swap you might incur
additional overhead compared to a hand-made correct implementation;
that's an implementation issue.


Unless you've specified less overhead, in which case it's a spec issue
too :)

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

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