Re: [boost] Boost memory management guidelines

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2003-08-30 09:18:11

On Saturday, August 30, 2003, at 9:31 AM, Peter Dimov wrote:

> The stateful allocator problem is a thorny issue too, since to allow
> stateful allocators, one needs to specify whether the stored allocator 
> is
> part of the logical state of the object. IE
>
> vector<T, A> v1(a1);
> vector<T, A> v2(a2);
>
> v1 = v2; // which allocator does v1 hold now?

Just to throw in my .02:

v1 holds the same allocator as it was constructed with.  Rationale:  
Allocator state should stay with the memory it allocates so that it can 
deallocate it when the time comes (much like the shared_ptr 
philosophy).  Since vector assignment does not transfer ownership of 
memory, it should not assign allocators.

But consider:

swap(v1, v2);

Here memory ownership is swapped between the vectors.  Therefore, imho, 
allocator state should also be swapped.

(purposefully not addressing or extending the above argument to 
function)

-Howard