----- Mensaje original ----- De: Peter Dimov <pdimov@mmltd.net> Fecha: Viernes, Marzo 4, 2005 0:32 am Asunto: Re: [boost] [congif] BOOST_BEFRIEND_TEMPLATE, BOOST_PRIVATE

Jonathan Turkanis wrote:

...

Hi,

<boost/shared_ptr.hpp> contains the following in the public section of the class definition (reformatted):

// Tasteless as this may seem, making all members public // allows member templates to work in the absence of member // template friends. (Matthew Langston)

#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS

private:

template<class Y> friend class shared_ptr; template<class Y> friend class weak_ptr;

#endif

T * px; // contained pointer detail::shared_count pn; // reference counter

This has become a pretty common technique, I believe. I certainly use it a lot, at any rate.

I'd like to suggest two macros which would allow code like the above to be simplified as follows:

BOOST_PRIVATE: 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. ;-)

Well, I think there are situations were it'd improve readability: Example 1: previous section was not public #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS private: template<class Y> friend class shared_ptr; template<class Y> friend class weak_ptr; #else public: #endif Example 2: derivation class Derived: #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS private else public #endif Base { ... }; Joaquín M López Muñoz Telefónica, Investigación y Desarrollo