Re: 2nd: [boost] shared_ptr proposal

From: Peter Dimov (pdimov_at_[hidden])
Date: 2001-07-13 09:37:37

From: "Beman Dawes" <bdawes_at_[hidden]>
>  >What are the complexity requirements of the boost::shared_ptr<> member
>  >functions?
>
> They are currently unspecified.  At least for now, that's probably
> best.  See below.

IOW, a linked-list implementation is conforming. This is good. :-)

>  >An interesting related question is "why does shared_ptr have use_count?"
>
> As an aid to writing test cases and debugging displays.  One of the
> progenitors had use_count(), and it was useful in tracking down bugs in a
> complex project that turned out to have cyclic-dependencies.

This should probably be documented (along with the decision to not specify
complexity requirements.)

Why is this important? Because some nice interface additions to shared_ptr
(my shared_ptr_id proposal, for instance) would be inappropriate under a
linked-list implementation.

Perhaps this deserves a new FAQ entry:

Q: Why doesn't shared_ptr provide (your pet feature here)?
A: Because (your pet feature here) would mandate a reference counted
implementation. This is not the intent.

--
Peter Dimov
Multi Media Ltd.