Re: [boost] Re: Re: ?

From: Greg Colvin (Gregory.Colvin_at_[hidden])
Date: 2002-08-29 16:06:53

At 01:24 PM 8/29/2002, Larry Evans wrote:
>Greg Colvin wrote:
>
>>At 11:31 AM 8/29/2002, Philippe A. Bouchard wrote:
>> 
>[snip]
>
>>>   
>>My guess is that placement new is necessary so that you
>>can capture the address of the shared object, yes?
>>
>> 
>It's only purpose, I believe, is to avoid two allocations instead of
>one.  In other words, instead of a detached reference count, as
>with shared_ptr, the reference count is allocated in the same
>block of memory as the object.

Which is what makes it possible to retrieve the counter, given
a pointer into the object, or vice versa.  Or at least to do it
quickly.  OK.  But then I still say that ptr<T> can just hold an
actual T*, and the rest of Phillippe's machinery should be
unnecessary.