Re: [boost] [utility/swap] Okay to add array support to Boost.Swap (sandbox/swap)?

From: David Abrahams (dave_at_[hidden])
Date: 2008-06-24 21:21:52

Howard Hinnant wrote:
> On Jun 23, 2008, at 3:54 PM, David Abrahams wrote:
> 
>> I haven't formed an opinion yet, but the fact remains that swapping a
>> boost::array would have very different efficiency characteristics from
>> swapping the analogous std::vector, so we ought to think it through
>> carefully.
> 
> If it helps, here is a test program using gcc 4.0.1:
> 

> On my machine:
> 
> $ g++ -O3 test.cpp
> $ ./a.out
> swap1 time is 0.172796 seconds
> swap2 time is 1.3e-05 seconds
> 
> I also note that swap1 can throw exceptions and swap2 can't.  I also
> note that move semantics will greatly speed swap1, and make it nothrow,
> but I still expect swap1 with move semantics to be about twice as slow
> as swap2.

Your program gives about the results I'd have expected for the case you
tested, but it doesn't address what I was concerned about.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com