[boost] Re: AW: Direct vs. indirect shared_ptr

From: David Abrahams (abrahams_at_[hidden])
Date: 1998-12-07 17:11:55

Beman Dawes (beman_at_[hidden]) wrote:

>I
>don't have any problem requiring the specific name (say "use_count")
>for the embedded counter.

I do: It could cause unneccessary collisions and unintended effects!
It's so easy to use base class; why not do it that way?

namespace boost {

template <class T = std::size_t>
struct reference_counted {
  T use_count;
};

template <class T, class RC = std::size_t >
class embedded_ptr
{
  ...
private:
  // All reference count manipulations go thru this member function
  inline RC& count() const
  {
     reference_counted<RC>& counted = *this->p;
     return counted.use_count;
  }
};

}

Intrusively reference-counted classes would then inherit publicly from 
boost::reference_counted<>.

-Dave

P.S. If you don't like the 2nd optional argument from embedded_ptr for 
types that want a different reference count type, we could ask the user 
to specialize boost::reference_counted_traits<> for their 
intrusively-counted types, supplying a count_type.

--------------------------------------------------------------
David Abrahams * Mark of the Unicorn, Inc. * abrahams_at_[hidden]

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