Re: [boost] [smart_ptr] release()

From: Peter Dimov (pdimov_at_[hidden])
Date: 2008-08-30 07:44:10

Phil Bouchard:

> template<class P, class D, class A>
>    class sp_counted_impl_pda: public sp_counted_base
>    {
>        ...
>        virtual void destroy() // nothrow
>        {
>            typedef typename A::template rebind< this_type >::other A2;
>
>            A2 a2( a_ );
>
>            this->~this_type();
>            a2.deallocate( this, 1 );
>            // ugh!
>        }
>    };
>
> This is ill-formed code.

I don't think you know what "ill-formed" means.

> The way shared_ptr works right now, the pool is going to be copied 
> entirely on to the sp_counted_impl_pda object.

shared_ptr requires that the A argument conforms to the Allocator 
requirements in the standard (Table 40 in N2691):

a1 == a2 bool returns true iff storage allocated from each can be 
deallocated via the other. operator== shall be reflexive, symmetric, and 
transitive.

X a1(a); post: a1 == a

X a(b); post: Y(a) == b, a == X(b)

Your example is not an Allocator.