Re: [boost] [Root Pointer] Benchmark

Subject: Re: [boost] [Root Pointer] Benchmark
From: Phil Bouchard (philippeb8_at_[hidden])
Date: 2016-03-15 20:31:23

On 03/15/2016 07:25 PM, Glen Fernandes wrote:
>
> You mentioned a while back that you preferred:  p.reset(new
> X(args...)); because it was intuitive, and in your opinion more
> intuitive than: p = f<X>(args...);
>
> Nobody would have any issue with that. But people would certainly have
> issue with: Y::Z b(a); p = new (b) Q(b, args...); compared to  p =
> g<X>(a, args...);

Well first if you have a as an r-value:
p = g<X>(a, args...)

That means the allocator parameter must be constant:
g<X>(Allocator const &, arg...)

If it's constant it won't be able to change its internal state.  I 
thought that was the purpose of having instantiable allocators?

I can write a wrapper function for:
p1 = new (a1) node(a1, 1, 'a');

But not for the declaration of the allocator:
boost::node<U, Allocator<U> >::allocator_type a1(n1, m1);

Why?  Because you allocate node<U>s, not Us.  I could write some 
node_traits<> helper:

template <typename T, template <typename> class A>
     {
         typedef typename boost::node<T, A<T> >::allocator_type 
allocator_type;
     };

So that the declaration becomes:
boost::node_traits<U, Allocator>::allocator_type a1(n1, m1);

But that's all I can do.

-Phil