Re: [boost] Re: Smart pointers: One more implementation +question

From: Dave Abrahams (dave_at_[hidden])
Date: 2003-02-05 12:13:48

On Wednesday, February 05, 2003 11:14 AM [GMT+1=CET],
David B. Held <dheld_at_[hidden]> wrote:

> "Pavel Vasiliev" <pavel_at_[hidden]> wrote in message
> news:119691015.20030205155314_at_mpen.bas-net.by...
> > [...]
> > Implementing of refc_ptr as a set of policies is also possible, but
> > currently that seems to be overkill, both in unnecessary
> > complexity and performance losses. Though this my opinion may
> > change with time.
>
> I certainly hope there aren't performance losses!  That's one of the
> main motivations for writing custom policies.  How would there be
> a performance loss with SmartPtr?

Lots of ways. For example, the smart pointer objects could be bigger than
neccessary.

> > Conclusion: IMO, policy-based implementations like
> > Loki::SmartPtr<> and "fixed" ones like boost::shared_ptr<T> or
> > my refc_ptr<T> serve different needs. Do I say something new?
> > Hardly.
>
> You're right for now, but if we get template aliasing...even so,
> it is possible to emulate almost any pointer with SmartPtr (though
> some are admittedly more difficult than others), and even though
> this requires a non-default policy set, a type generator wrapper
> will usually suffice.

Type generators are overkill, since unlike with iterator adaptors there's no
need to preserve type identity.  Normal inheritance will work just fine.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com