RE: [boost] [Review] Boost Graphs Library (GGCL)

From: jsiek_at_[hidden]
Date: 2000-08-30 16:36:18

Gary Powell writes:
 > This works for one additional class type. How about three?
 > template<class Compare, class Equal, class Allocator>
 > struct garys_contianerS {};
 > 
 > template<class Compare, class Equal, class Allocator, class T>
 > struct container_gen<garys_containerS<Compare,Equal,Allocator>, T>
 > {
 >   typedef garys_container<T, Compare<T>, Equal<T>, Allocator> type;
 > };
 > 
 > I think this is prohibited. Its fine for the namespace ggcl, but not std.

If you want to use template template parameters in the selectors
that's your own business ;)

namespace gary {
  template< template <class T> class Compare, 
            template <class T> class Equal, 
            class Allocator>
  struct contianerS {};
}
namespace std {
  template<class Compare, class Equal, class Allocator, class T>
  struct container_gen<gary::containerS<Compare,Equal,Allocator>, T>
  {
    typedef gary::container<T, Compare<T>, Equal<T>, Allocator> type;
  };
}

This should work just fine, and I don't think there is a std namespace
problem:

17.4.3.1 "... A program may add template specializations for any
standard library template to namespace std. Such a specialization
(complete or partial) of a standard library template results in
undefined behaviour unless the declaration depnds on a user-defined
name of external linakage and unless the specialization meets the
standard library requirements for the original template"

Cheers,

Jeremy