Re: [boost] rvalue ref best practices?

Subject: Re: [boost] rvalue ref best practices?
From: Sebastian Redl (sebastian.redl_at_[hidden])
Date: 2012-06-15 09:59:37

On 15.06.2012 14:36, Mathias Gaunard wrote:
> On 15/06/2012 06:42, Dave Abrahams wrote:
>> But you usually can't tell the difference between bar() failing and the
>> assignment failing, and it's perfectly natural for a failed assignment
>> to change the assignee.
>
> I can tell perfectly fine with
>
> T foo;
>
> try
> {
>   foo = bar();
> }
> catch(...)
> {
> }
>
> // what state is foo in now?
Assume T is std::array<E, 32>, where E isn't movable and its copy 
constructor/assignment might throw. std::array's assignment operator 
gives only the basic guarantee. So if an exception occurred in the 
assignment operator, you know that the vector is array, but you don't 
know anything about its contents. It might be a wild mixture of what was 
in it before the assignment and the elements returned from bar.

Sebastian