Re: [boost] auto_vector - vector with auto_ptr semantics

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2002-02-04 21:40:17

On Monday, February 4, 2002, at 09:18  PM, Rainer Deyke wrote:

> std::vector<int> g()
> {
>   std::vector<int> first, second;
>   // Do various operations on 'first' and 'second' here.
>   return (first.size() > second.size()) ? first : second;
> }
>
> std::vector<int> v(g());
>
> The compiler can't construct the return value "in place" because it
> does not know which of the two vectors will be returned at the time of
> construction.
>
>
>>  But here's another possibility in case your compiler
>> is weak in this area:
>>
>> T b(std::move(f()));
>>
>> (assuming we can get the move from temporary worked out)
>
> I don't think this will work because by the time 'f' returns, the
> temporary will already be copied.

Good example!

How 'bout:

std::vector<int> g()
{
   std::vector<int> first, second;
   // Do various operations on 'first' and 'second' here.
   return std::vector<int>(std::move(first.size() > second.size() ? 
first : second));
}

std::vector<int> v(std::move(g()));

?

-Howard