Re: [boost] Re: Proven ptr<>

From: Greg Colvin (Gregory.Colvin_at_[hidden])
Date: 2002-08-11 21:49:01

At 02:30 PM 08/11/2002, Philippe A. Bouchard wrote:
>> As for the implementation, I think there are better approaches that
>> would cause no penalty for get().  The usual trick is to use size-
>> segregated storage pools set up so that one can get from an interior
>> pointer to an object header very quickly.  The Boost pool implementation
>> can probably be tweaked for this purpose.  Then a mumble_ptr<T> can just
>> store a proper T*, so get() has no overhead, and the arithmetic to
>> access the count is paid for only when needed.
>
>Uhh...  pool is an accelerated memory allocator, but still is a memory
>allocator.  If we would use the standard malloc(), reconstruction of
>containers would be like allocating a separate reference count.  Also get()
>is not that slow: 1 more second for 1000 sorts of a 10000 element container.

I'm not sure of the tradeoffs, but you have to allocate a
reference count anyway, no?  And you are paying an extra
cost in space of about N*(N/2) offsets for a system with
N ptr<> types, yes?