Re: [boost] Re: shared_ptr bug?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2001-10-21 19:33:35

At 05:52 PM 10/18/01 +0000, williamkempf_at_[hidden] wrote:
 >--- In boost_at_y..., "Fernando Cacciola" <fcacciola_at_g...> wrote:
 >>
 >> ----- Original Message -----
 >> From: David Abrahams <david.abrahams_at_r...>
 >> To: <boost_at_y...>
 >> Sent: Thursday, October 18, 2001 12:24 PM
 >> Subject: Re: [boost] shared_ptr bug?
 >>
 >>
 >> > Can we do better with a single-pointer-chained-count design?
 >> >
 >> > +-ptr-+     +-count-+     +-target-+
 >> > |     |     |   |   |     |        |
 >> > |  *=======>| 1 | *======>|        |
 >> > |     |     |   |   |     |        |
 >> > +-----+     +---+---+     +--------+
 >> >
 >> I'm not aware of this design. Could you point me to any online
 >reference
 >> that I can look at?
 >
 >If I understand the picture, what's proposed is going from this:
 >
 >template<typename T> class shared_ptr {
 >  // removed for clarity
 >  T* px;
 >  long* pn;
 >};
 >
 >to this:
 >
 >template<typename T> class shared_ptr {
 >  // removed for clarity
 >  struct count { T* px; long n; }
 >  count* pc;
 >};
 >
 >This may well simplify the implementation, but it would add a level
 >of indirection when dereferencing the "pointer".

That was the rationale for rejecting the indirect approach.

--Beman