[Boost-users] [graph] Bug - add_edge (adjacency_list) does not report if edge already exists as stated in documentation

From: Martin Mann (mmann_at_[hidden])
Date: 2008-08-06 06:07:50

Hi,

I encountered the following problem :

a successive call with equal parameters u, v, and g of

============================================================
std::pair<edge_descriptor, bool>
    add_edge(   vertex_descriptor u
              , vertex_descriptor v
              , adjacency_list&   g )
============================================================

yields both times "RESULT.second == true".

But the documentation states, that only in case it is NOT PRESENT it 
should be true, which is obviously wrong for the second call.

If I use the "edge(u,v,g)" method to check if the edge exists I get the 
correct result of "edge(u,v,g).second == false" before the first call 
and "edge(u,v,g).second == true" after the first and before the second call.

So the problem is all about the add_edge function and I think it's more 
a bug than a feature. Because otherwise the bool-flag is obsolete or 
reports something totally different.

Cheers,

Martin

============================================================
   The boost graph class I use
============================================================

   //! The properties available for the nodes of a CoreGraph
typedef	boost::property< boost::vertex_index_t, size_t
         , boost::property< boost::vertex_name_t, std::string
         > >
                 CoreGraph_NodeProperties;
        
   //! The properties available for the edges of a CoreGraph
typedef	boost::property< boost::edge_name_t, std::string
         >
                 CoreGraph_EdgeProperties;
        
   //! The definition of a the internal graph representation
typedef boost::adjacency_list< boost::vecS
                                , boost::vecS
                                , boost::undirectedS
                                , CoreGraph_NodeProperties
                                , CoreGraph_EdgeProperties
             >  CoreGraph;

============================================================