[Boost-users] [BGL] Unable to sort list of edge_descriptors

Subject: [Boost-users] [BGL] Unable to sort list of edge_descriptors
From: Mike Douglass (douglassm13_at_[hidden])
Date: 2010-11-06 05:04:57

I'm trying to sort a list of edge_descriptors, but I get the compiler error 
described below.



typedef adjacency_list < vecS, vecS, bidirectionalS >::edge_descriptor 
edgeDescriptor; // defined globally

  template < typename Graph, typename edgeDescriptor >
    struct SortByName : public binary_function<edgeDescriptor, edgeDescriptor, 
bool>
 {
            bool operator()(const Graph & g, const edgeDescriptor& a, const 
edgeDescriptor& b)
          {
                return g[a].eName < g[b].eName;
          }

 };


  template < typename Graph >
    void Sort_Test(Graph & g)
  {

    typedef std::list<edgeDescriptor> edge_list;
    typename graph_traits<Graph>::edge_iterator edge_iter, edges_end;

        edge_list A;

        for (tie(edge_iter, edges_end) = edges(g); edge_iter != edges_end; 
++edge_iter)
                A.push_back(*edge_iter);

        for (edge_list::iterator i = A.begin(); i != A.end(); ++i)
                cout <<  " *i = " << " " << g[*i].eName << "\n";

        // If the following line is commented out the program compiles and runs 
OK.
        A.sort(SortByName< typename Graph, typename edgeDescriptor >());
        //With the above line uncommented the compiler says:

/*
./Includes/Utilities.cpp: In function ‘void Sort_Test(Graph&)’:
./Includes/Utilities.cpp:539: error: wrong number of template arguments (1, 
should be 2)
./Includes/Utilities.cpp:513: error: provided for ‘template<class Graph, class 
edgeDescriptor> struct SortByName’
make: *** [plc] Error 1
*/

 }

 But clearly there are two template arguments - < typename Graph, typename 
edgeDescriptor >

Thanks