Re: [boost] Re: downcasting smart pointers (suggested code)

From: Peter Dimov (pdimov_at_[hidden])
Date: 2001-07-24 16:07:46

From: "Greg Colvin" <gcolvin_at_[hidden]>
[...]
> > Still, I prefer that shared_dynamic_cast<> be left as an option. More
> > focused (less generic) interfaces are less error prone, when genericity
is
> > not required.
>
> Yes, although I think a shared_ptr member function is the right
> way to go for that purpose.

A member function has that awkward (when it even works)

p.template cast<X>()

syntax. :-)

I'd provide a constructor

template<class U> shared_ptr<T>::shared_ptr(shared_ptr<U> const &,
dynamic_cast_tag);

as a helper (to avoid the troublesome friend declarations) and a free
function

template<class U, class T> shared_ptr<U> shared_dynamic_cast(shared_ptr<T>
const & p)
{
  return shared_ptr<U>(p, dynamic_cast_tag);
}

--
Peter Dimov
Multi Media Ltd.