Re: [BGL] How can I use vertex object rather than integer?

From: a_schweitzer (a_schweitzer_at_[hidden])
Date: 2002-06-06 20:01:46

I'm not sure, but after playing with this for a while, I think the 
vertex and edge objects (vertex_descriptor, edge_descriptors) used by 
the graphs are opaque handles: you can't get at their contents 
directly.

To attach properties to the vertices or graph I did the following:
-> In the adjacency list template declaration, specify a vertex 
property class and an edge property class.
-> This class is some version of a boost "property" class. 
-> Before you define this class you use a macro to define a string 
identifying it. 
-> To access your data you call get(id_string, Graph), which returns 
a "property map" class. The property map class seems to be a boost 
way of doing things.
-> Then you get your data from the map, using either a different 
verstion of get or operator []. So what I did ended up doing to get 
data was something like the following, assuming I had a 
vertex_descriptor v, say from an add_vertex:
int iColor = get(vertex_color, MyGraphObject)[v];

Part of what I ended up doing was:
//In properties.hpp I added:
  BOOST_DEF_PROPERTY(vertex, custom);
  BOOST_DEF_PROPERTY(edge, type);
  BOOST_DEF_PROPERTY(edge, custom);

//Then I defined:
typedef property < edge_name_t, int, property < edge_type_t, 
eEdgeTypes > > EProps ;
//This gives edges two properies: an int accessed through edge_name
// and enumerated eEdgeTypes accessed through edge_type

class VertexProperties
{
public:
        char				m_cName;
        int				m_iDFSOrder;
        int				m_iRootIdx;
        int				m_iComponent;
        int				m_iComponentHeight;
        bool				m_bSelfLoop;
        VertexProperties(){memset(this, 0, sizeof(*this));}
};
typedef property < vertex_custom_t, VertexProperties, property < 
vertex_index_t, int > > 
        VProps;
//That gives each vertex a VertexProperties class accessible through 
//vertex_custom, and an integer index property accessible through 
//vertex_index. 

//finally here's the graph definition:
typedef adjacency_list<	listS,vecS,directedS,VProps,EProps > Graph; 
        

//to access my custom properties I would do something like this:

Graph g;
vertex_descriptor v;
get(vertex_custom, g)[v].m_iDFSOrder = iNextDFSOrder++;

Gloomy PS: I got all my code working --- and then the MS VC++ 
compiler stopped working, giving me internal errors. On Windows CE 
(Platform Builder) I couldn't get it working at all. 

--- In Boost-Users_at_y..., "¹Ú±â¼ö" <yg-boost-users_at_m...> wrote:
> for example,
> 
> class Node
> {
> public:
>     int m_id;
> };
> 
> class Edge
> {
> public:
>   int from_node_id;
>   int to_node_id;
> };
> 
> How can I use this class to make graph?
> many examples show only integer id graph..
> 
> thanks in advance
> 
> 
> ----------------------------------------
> Ki-Soo, Park
> HP: 82-11-9040-4957
> e-mail: park_at_e...
>            wfms123_at_h...