diff -r ee5959aa4410 -r c280de819a73 src/work/klao/tag_demo.cc
--- a/src/work/klao/tag_demo.cc	Sun Apr 17 18:57:22 2005 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,95 +0,0 @@
-#include <iostream>
-#include <boost/utility.hpp>
-
-using namespace std;
-using namespace boost;
-
-struct True {
-  static const bool value = true;
-};
-struct False {
-  static const bool value = false;
-};
-
-// Here are some graph structures. Some of them define the type "OneTag"
-// to True or False, some does not. Not defining a tag is (or at least
-// should be) equivalent to defining it to "False".
-struct Graph1 {};
-struct Graph2 {
-  typedef True OneTag;
-};
-struct Graph3 {
-  typedef False OneTag;
-};
-
-
-/**************** The first method to use tags ****************/
-
-template <typename Graph, typename Enable = void>
-struct HasOneTag {
-  typedef False TheTag;
-};
-
-// specialization for those graphs which defined the tag to be true:
-template <typename Graph>
-struct HasOneTag<Graph, typename enable_if<typename Graph::OneTag>::type > {
-  typedef True TheTag;
-};
-
-template <typename Graph>
-int cn1(const Graph &, False) {
-  return 0;
-}
-
-template <typename Graph>
-int cn1(const Graph &, True) {
-  return 1;
-}
-
-template <typename Graph>
-int cn1(const Graph &g) {
-  return cn1(g, typename HasOneTag<Graph>::TheTag());
-}
-
-/**************** The second method ****************/
-
-// An artificial type to provoke a conversion to avoid ambuguity...
-template <typename T>
-struct Wrap {
-  const T &value;
-  Wrap(const T &t) : value(t) {}
-};
-
-template <typename Graph>
-typename enable_if<typename Graph::OneTag, int>::type
-_cn2(const Graph &) {
-  return 1;
-}
-
-template <typename Graph>
-int _cn2(Wrap<Graph>) {
-  return 0;
-}
-
-template <typename Graph>
-int cn2(const Graph& g) {
-  return _cn2<Graph>(g);
-}
-
-
-int main() {
-  Graph1 g1;
-  Graph2 g2;
-  Graph3 g3;
-
-  cout << "The first method:\n";
-  cout << "G1: " << cn1(g1) << endl;
-  cout << "G2: " << cn1(g2) << endl;
-  cout << "G3: " << cn1(g3) << endl;
-
-  cout << "The second method:\n";
-  cout << "G1: " << cn2(g1) << endl;
-  cout << "G2: " << cn2(g2) << endl;
-  cout << "G3: " << cn2(g3) << endl;
-
-}