Re: [Boost-users] Problems with property_maps

28 Feb 2010


      On Sat, 27 Feb 2010, Trevin Murakami wrote:
...
Hello all.
I'm having issues getting property maps to work properly with my
custom adjacency_list.  Here's a snippet of the code:
// Definitions
// define some of the properties the graphs will have
// http://www.boost.org/doc/libs/1_42_0/libs/graph/doc/using_adjacency_list.htm...
struct posx_t { typedef vertex_property_tag kind; };
struct posy_t { typedef vertex_property_tag kind; };
typedef property VertexPosX;
// chain to add in posy
typedef property VertexPos;
// chain to add in vertex_index
typedef property VertexProperty;
// define our special graph
typedef adjacency_list > AGraph;
...
template<class T>
void boostToVAGraph(const AGraph & g,
      			const int num_nodes, const int num_edges,
      			T ** idata,
      			T ** odata,
      			unsigned int ** segment_descriptor,
      			unsigned int ** cross_pointers,
      			unsigned int ** head_flags,
      			T ** reference,
      			const testrigOptions & testOptions)
{
  typedef AGraph Graph;
// define the manipulator for our special properties
  // http://www.boost.org/doc/libs/1_42_0/libs/graph/doc/using_adjacency_list.htm...
  // requires property_map.hpp
  // BROKEN!!!!!
  property_map::type
      getposx = get(posx_t(), g);
  property_map::type
      getposy = get(posy_t(), g);
...
I used another function to generate the AGraph and apply values.  And
using property map there seems to work.  However, I then pass it to
this function using:
boostToVAGraph(g, num_nodes, num_edges, idata, odata, segment_descriptor,
      cross_pointers, head_flags, reference,
      testOptions);
On compile, I get this error:
1>agraph.cpp
1>c:/Documents and Settings/All Users/Application Data/NVIDIA
Corporation/NVIDIA GPU Computing SDK/C/src/test/agraph.cpp(94) : error
C2440: 'initializing' : cannot convert from
'boost::adj_list_vertex_property_map'
to 'boost::adj_list_vertex_property_map'
1>        with
1>        [
1>            Graph=AGraph,
1>            ValueType=int,
1>            Reference=const int &,
1>            Tag=posx_t
1>        ]
1>        and
1>        [
1>            Graph=AGraph,
1>            ValueType=int,
1>            Reference=int &,
1>            Tag=posx_t
1>        ]
1>        No constructor could take the source type, or constructor
overload resolution was ambiguous
The error seems to be that you are trying to convert from the const 
property map type (because the graph in boostToVAGraph is const) to the 
non-const one (property_map::type).  I believe you would 
want property_map::const_type as the property map type in 
your function instead.

-- Jeremiah Willcock