Re: [boost] [Variant] Documentation Questions/Notes

Subject: Re: [boost] [Variant] Documentation Questions/Notes
From: Dave Abrahams (dave_at_[hidden])
Date: 2012-10-27 16:49:10

on Sat Oct 27 2012, Steven Watanabe <watanabesj-AT-gmail.com> wrote:

> AMDG
>
> On 10/27/2012 10:50 AM, Dave Abrahams wrote:
>> 
>> <snip>
>> 
>> - The  "temporary heap backup" technique seems to have a hole:
>> 
>>    1. Copy-construct the content of the left-hand side to the heap;
>>       call the pointer to this data backup.
>>    2. Destroy the content of the left-hand side.
>>    3. Copy-construct the content of the right-hand side in the
>>       (now-empty) storage of the left-hand side.
>>    4. In the event of failure, copy backup to the left-hand side
>>       storage.
>>    5. In the event of success, deallocate the data pointed to by
>>       backup.
>> 
>>   What happens in the event of a failure in step 4?
>> 
>
> backup is a pointer.  Copying it can't fail.

Ah, thanks.  I guess the docs could make that clearer.

-- 
Dave Abrahams
BoostPro Computing                  Software Development        Training
http://www.boostpro.com             Clang/LLVM/EDG Compilers  C++  Boost