Re: [Boost-Users] Re: Q: Graphs. Sorting edges. Possible? How to?

From: Jeremy Siek (jsiek_at_[hidden])
Date: 2002-11-07 10:34:17

Hi Richard,

On Wed, 6 Nov 2002, loopylozzysdad wrote:
Richar> Hi,
Richar>
Richar> I did work out the answer to my own question. I can't explain
Richar> how/why this works but by copying from the header files I ended up
Richar> with the following changes to Jeremy's posted code...[1]
Richar> Good luck if you want it - please don't ask me to explain it!

I can explain it :)

As hinted by the #ifndef, the commented out version of container_gen uses
partial specialization. The first parameter to container_gen is
specialized, but the second is left as a template. Partial spec. is not
yet supported by VC++ (but soon will be).

The change you made is one of the classic ways of replacing partial
specialization with full specialization. You remove the unspecialized
parameter, and instead add a nested class template (here it is bind_).

Cheers,
Jeremy

Richar> Richard
Richar>
Richar>
Richar> [1]
Richar> Comment out from original ....
Richar> //struct ordered_set_by_nameS { };
Richar>
Richar> //#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
Richar> //namespace boost {
Richar> //	template <class ValueType>
Richar> //struct container_gen<ordered_set_by_nameS, ValueType> {
Richar> //	typedef std::multiset<ValueType, order_by_name<ValueType> >
Richar> type;
Richar> //	};
Richar> //template <>
Richar> //struct parallel_edge_traits<ordered_set_by_nameS> {
Richar> //	typedef allow_parallel_edge_tag type;
Richar> //	};
Richar> //	}
Richar> //#endif
Richar>
Richar> Replaced by .....
Richar> namespace boost {
Richar> 	struct orderedmultisetS  {
Richar> 		template <class T>
Richar> 	struct bind_ { typedef std::multiset<T, order_by_name<T> >
Richar> type; };	// std::less<T>
Richar> 		};
Richar>
Richar> 	BOOST_CONTAINER_SELECTOR(orderedmultisetS);
Richar>
Richar> 	template <>
Richar> 		struct parallel_edge_traits<orderedmultisetS> {
Richar> 			typedef disallow_parallel_edge_tag type;
Richar> 			};
Richar>
Richar> 	}
Richar>

----------------------------------------------------------------------
 Jeremy Siek                          http://php.indiana.edu/~jsiek/
 Ph.D. Student, Indiana Univ. B'ton   email: jsiek_at_[hidden]
 C++ Booster (http://www.boost.org)   office phone: [phone]
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