Re: [Boost-users] How to extending algorithms with visitors

From: Giulio Veronesi (giulio_veronesi_at_[hidden])
Date: 2005-09-15 01:50:14

Hi Jeremy,

Thank you very much. I resolved the problem using the new version of 
Dijkstra's algorithm that includes a named parameter for recording 
predecessors.

Now I've another problem and I've no idea how to resolve it. I'd like to 
extract all possible shortest path from a sorce to a destination... not 
only one path. Please, could you help me to resolve this problem?

Thanks a lot in advance,
Giulio

Jeremy Siek ha scritto:
> Hi Giulio,
> 
> Glad you're enjoying the BGL :)
> 
> Hmm, I don't see anything wrong... perhaps the error is even
> earlier in the source file, causing the compiler's parser
> to become very confused.
> 
> If you want more help you'll need to send us a complete
> program that we can compile. Also, you'll need to tell
> us the compiler and its version number.
> 
> Cheers,
> Jeremy
> 
> On Sep 14, 2005, at 11:01 AM, Giulio Veronesi wrote:
> 
>>Hi all,
>>
>>I'm enjoying learning the boost graph library. I'm
>>trying to use the Dijkstra algorithm and try to store
>>the shortest path as explained in the subsection
>>"Extending Algorithms with Visitors" of the section
>>"Quick Tour" of the BGL user guide.
>>
>>When I try to compile my code, I get the following
>>error message:
>>
>>mesh.cpp:38: error: expected constructor, destructor,
>>or type conversion before '<' token
>>mesh.cpp:38: error: expected `;' before '<' token
>>
>>where line 38 is highlighted in the following portion
>>of code.
>>
>>Could you help me to resolve this problem?
>>
>>Thanks in advance,
>>Giulio
>>
>>
>>template <class PredecessorMap>
>>class record_predecessors : public dijkstra_visitor<>
>>  {
>>  public:
>>    record_predecessors(PredecessorMap p)
>>      : m_predecessor(p) { }
>>
>>    template <class Edge, class Graph>
>>    void edge_relaxed(Edge e, Graph& g) {
>>      // set the parent of the target(e) to source(e)
>>      put(m_predecessor, target(e, g), source(e, g));
>>    }
>>  protected:
>>    PredecessorMap m_predecessor;
>>  };
>>
>>template <class PredecessorMap>
>>line 38: record_predecessors<PredecessorMap>
>>make_predecessor_recorder(PredecessorMap p)
>>{
>>  return record_predecessors<PredecessorMap>(p);
>>}
>>
>>
>>
>>
>>
>>
>>
>>
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> 
> 
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