Re: [boost] [shared_ptr] constructor accepting auto_ptr

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-12-07 12:14:05

Yuval Ronen wrote:
> Peter Dimov wrote:
>> The reference adds a strong exception safety guarantee. If the
>> shared_ptr constructor fails, the source auto_ptr is left intact.
>> Pass by value would have already zeroed out the source.
>>
>> If you want to achieve the equivalent of pass by value, you can use
>> an explicit .release().
>>
>> This warning would actually be an error on a stricter compiler.
>>
>> One happy day the compiler writers will bring us the rvalue
>> reference, the constructor will take auto_ptr &&, and all will be
>> well with the world. :-)
>
> Does that mean that on a stricter compiler, when passing a temporary
> auto_ptr, I *have* to use the '.release()' way, and *can't* get the
> strong exception guarantee?

Yes it does, but when your source is a temporary, it doesn't make any 
difference; even if it's left unchanged by the constructor, it will be 
destroyed at the end of the full expression, along with the pointee.