Re: Sequence points in new operator and constructor
on Wed Dec 10 2008, Chaos.A.D88-AT-gmail.com wrote:
Hi, can somebody please describe me one point?
How many sequence points there in this statement:
Foo *f = new Foo(Fn());
It interests me because of exception safety...
We knew, that one of the ways to write exception safe is to use RAII
idiom.
And let's consider that Fn() in my example returns pointer on some
dynamically allocated object. And Foo in it's constructor grabs it's
ownership.
So, this code will be exception safe if there is a sequence point
between memory allocation (new operator), which may throw
std::bad_alloc, and constructor.
Is there any guarantee that new never throws it's exception AFTER left
side with all arguments starts calculating?
I don't remember the details, but to avoid sequence point traps I always
follow Peter Dimov's guideline:
http://www.boost.org/doc/libs/1_37_0/libs/smart_ptr/shared_ptr.htm#BestPractices
HTH,
--
Dave Abrahams
BoostPro Computing
http://www.boostpro.com
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