Re: [boost] [shared_ptr] Design question about make_shared

Subject: Re: [boost] [shared_ptr] Design question about make_shared
From: Loïc Joly (loic.actarus.joly_at_[hidden])
Date: 2011-06-15 17:43:16

Le 15/06/2011 13:15, Peter Dimov a écrit :
> Stephan T. Lavavej wrote:
>> Right, that's what I was trying to say - internally, they are 
>> coupled, yet make_shared goes out of its way to be a free function.
>
> My initial implementation of boost::make_shared was a self-contained 
> header that didn't require any changes to shared_ptr (it would have 
> worked with std::tr1::shared_ptr as well as it worked with 
> boost::shared_ptr). This can only be done with a free function.
>
> Now, this copied around the deleter a few times more than necessary 
> and created problems with over-aligned types, so you're right that an 
> optimized implementation needs support from shared_ptr. :-) (However, 
> it can be argued that this support - the ability to ask for a deleter 
> of a specific type to be default-constructed in place by shared_ptr - 
> should be offered to users as well, not just to make_shared.)

Thank you for all those answers. I was wondering if ADL had something to 
do in this decision (I could not see how, at least not in a positive 
way), but it looks like this was not a criterion.

-- 
Loïc