Re: [boost] Re: [bug]: optional<T> fails on self-assignment

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-02-16 08:29:37

David Abrahams wrote:
> "Joe Gottman" <jgottman_at_[hidden]> writes:
>
>>
>>    I disagree.  This may ensure the basic exception-safety
>> guarantee, but most code that uses optional<T> will use
>> T::operator=() at some point or other.  So if T::operator=() is not
>> exception-safe
>
> Whoa, here we go again!  You seem to be assuming
>
>  basic exception-safety guarantee == "not exception-safe."
>
> That's just not true for any reasonable definition of
> "exception-safe."

No, he isn't assuming that. "Not exception safe" == "does not provide basic" 
in the above paragraph. Fernando's goal, IIUC, was to make 
optional<T>::operator= provide the basic guarantee even when T::operator= 
does not. We are arguing that this is not necessary and that 
optional<T>::operator= should just mirror the exception safety guarantee of 
T::operator= and T::T( T const & ).