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From: David Abrahams (dave_at_[hidden])
Date: 2005-03-06 03:30:06

"Jonathan Turkanis" <technews_at_[hidden]> writes:

> David Abrahams wrote:
>> "Peter Dimov" <pdimov_at_[hidden]> writes:
>>> Jonathan Turkanis wrote:
>>>> David Abrahams wrote:
>>>>> "Peter Dimov" <pdimov_at_[hidden]> writes:
>>>>>>> BOOST_BEFRIEND_TEMPLATE(shared_ptr, Y, 1)
>>>>>>> BOOST_BEFRIEND_TEMPLATE(weak_ptr, Y, 1)
>>>>>>> T * px; // contained pointer
>>>>>>> detail::shared_count pn; // reference counter
>>>>>> This doesn't look any better to me than the original, sorry. ;-)
>>>>> I agree with Peter. In fact, to me it looks significantly worse.
>>>> Well, there's no accounting for taste. ;-) I use similar macros a
>>>> lot in the Preboost Interfaces library.
>>> This has nothing to do with taste. The original version of the code
>>> can be understood immediately as it only relies on general C++
>>> knowledge. The macro-based version adds a level of indirection; you
>>> now need to look at the documentation or the definition of the
>>> macros.
>> Right. It would be different if the macros significantly raised the
>> abstraction level, but they don't.
> The reason I like the macros is that you only need one version of
> the code,

I consider the #ifdef idiom to be only "one version of the code", when
I look at it. I generally don't need protected members, so I put the
friends right between the public and private stuff, where it belongs:

  class fu
   private: // template friends
      template<class Y> friend class shared_ptr;
      template<class Y> friend class weak_ptr;

   private: // data members
      T* px;
      detail::shared_count pn;

Clean and quiet.

> and -- if you find the macro names intuitive -- the version with the macros
> reads like the version for conforming compilers.

Just wait till you start needing nontype template parameters.

> It's basically the same idea as BOOST_USE_FACET.

Never had to use that one.

Dave Abrahams
Boost Consulting

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