[boost] Re: policy-based smart pointers are EVIL! (was: Intrusive smart pointer)

From: Gennadiy Rozental (rogeeff_at_[hidden])
Date: 2002-04-19 11:28:37

"Peter Dimov" <pdimov_at_[hidden]> wrote in message
news:016701c1e798$59d28a60$1d00a8c0_at_pdimov2...
> From: "Dietmar Kuehl" <dietmar_kuehl_at_[hidden]>
> > OK, before you start thinking I have gone entirely stupid (which you
> > are, of course, free to think anyway), I want to clarify a little bit:
> > The problem with policy-based designs is that similar entities with a
> > similar intention become incompatible.
>
> You are right. In particular, the problem is that when library A uses
> smart_ptr<T, X> and library B uses smart_ptr<T, Y>, the authors of X and Y
> must know about each other in order to provide a conversion.

>
> shared_ptr<T>'s custom deallocator support deliberately doesn't use
another
> template parameter to avoid this possibility.
>

You keep repeating this argument, but I still do not see why is it
important.

1. Could you provide reallife example shouing that this is an issue.
2. Is this only smart_ptr related? What about iterator_adaptors for example?
3. Could you sketch you solution with current smart_ptr?

Gennadiy.