From: David Abrahams (dave_at_[hidden])
Date: 2003-10-01 10:52:32
Gregory Colvin <gregory.colvin_at_[hidden]> writes:
> Still wondering.
>
> On Tuesday, Sep 30, 2003, at 11:09 America/Denver, Gregory Colvin wrote:
>> Given
>>
>> template<typename T> shifted_ptr<T> make_shifted_ptr(cont T& t) {
>> return shifted_ptr(new(so) T(t));
>> }
>>
>> ... make_shifted_ptr(Stuff()) ...
>>
>> are compilers allowed to optimize away the copy and construct the
>> Stuff in place?
The copy of the shifted_ptr? Yes, of course. That's the RVO.
>> If so, do they?
Some do; some don't.
Oh, wait. You meant the copy of Stuff()? It's not meant to be a T
neccessarily. It's just any old argument to T's constructor. You
need a bunch of overloads for make_shifted_ptr to make the example
complete.
-- Dave Abrahams Boost Consulting www.boost-consulting.com