RE: [boost] downcasting smart pointers

From: Michael VanLoon (MichaelV_at_[hidden])
Date: 2001-03-19 18:01:40

> From: Greg Colvin [mailto:gcolvin_at_[hidden]]
> Sent: Monday, March 19, 2001 12:21 AM
> 
> From: Kevlin Henney <kevlin_at_[hidden]>
> > In message <034e01c0afc7$09032e50$37781990_at_[hidden]>, 
> Greg Colvin
> > <gcolvin_at_[hidden]> writes
> > >From: Eric Ford <eford_at_[hidden]>
> > >> I'm using the counted_ptr from 
> http://ootips.org/yonat/4dev/ which is
> > >> similar to boost's shared_ptr.  However, I've run into a 
> problem.  I'm
> > >> willing to switch to the boost smart pointers, if they offer a
> > >> solution
> > >> to my problem.  (But I'm guessing that a solution for 
> one would work for
> > >> the other.)  Any help with either would be appreciated...
> > >> 
> > >> I have an STL container of counted_ptr<A>'s.  At some 
> point I need to
> > >> do a dynamic downcast of a counted_ptr<A> to a 
> counted_ptr<B>.  How do
> > >> I do that?  
> > >
> > >Right now you don't.  It has been on our chronic list of
> > >missing features for a long time but no one has been
> > >motivated enough to contibute a solution.
> > 
> > I may be mistaken, but I thought it had been discussed and 
> possible code
> > samples had been posted some time back -- something like
> > dynamic_shared_cast.
> 
> Yes, but that's as far as it got.  I think the name was
> do_dynamic_cast, and it was supposed to work with both raw
> and smart pointers.   Now that we have boost/cast.hpp we
> have a home for such a beast, and could do worse than just
> implementing a polymorphic_cast for shared_ptr.

Actually I have written a fully-implemented polymorphic smart-pointer that
has been used for more than a year at my company.  I have been toying with
releasing it to the public, but need to get employer approval to do so.