Re: Exception guarantee question
On Oct 31, 9:39 pm, Noah Roberts <roberts.n...@gmail.com> wrote:
If you have a member function like:
void add_job(std::auto_ptr<job> new_job)
{
jobs.push_back(new_job.get());
job.release();
}
From Herb Sutter's Item 22 in "More Exceptional C++":
"If an exception is thrown, program state remains unchanged"...
"implies commit/rollback semantics".
I would say from the callers perspective this is not the case,
as the auto_ptr will certainly be modified, but if add_job were
a member function of a class, the state of that class would
remain unchanged (and to me that is the effect that you are
looking for). Therefore the definition of strong guarantee
depends on what one considers "the program". The strong
guarantee would certainly hold for the the state inside
the function, but not for the auto_ptr.
OTOH the reason you are using an auto_ptr in the first place
is to communicate the fact that ownership "shall" be
transferred (you are forcing it). To me intent is conveyed
by using the auto_ptr in this case, and I would prefer your
solution to Alf's.
When I see and auto_ptr parameter, I know better than to touch
the auto_ptr after the call. When I see a "bald" pointer
parameter, I might as well delete the pointer after the call...
add_job( job );
delete job; //Was it cloned??? Ownership???
Regards,
Werner