Re: [Boost-users] How to find edge between two vertices of undirected graph?

11 Jun 2010


      On Thu, 10 Jun 2010, Eric Fowler wrote:
...
It seems I do not have a mutable graph. This sort of raises another 
issue: how do I declare an object that is described by a concept? 
The best you can do is apply a concept checking class.  That doesn't 
filter the members so you can only use the MutableGraph-required 
functions, but it at least makes sure that the graph you have is a 
MutableGraph.
...
For example, in this case I know I need a MutableGraph, and I see from the doc (http://www.boost.org/doc/libs/1_43_0/libs/graph/doc/MutableGraph.html) that MutableGraphs
have certain properties, such as DefaultConstructible, etc. 
Now, how do I declare a MutableGraph, and know I have one? I know that:
 typedef adjacency_list LEN > DG;
What methods are missing?  Could you please try applying the MutableGraph 
concept checking class to the DG type and see what breaks?
...
More to the point, how do I read something like: 
template <class G>
  struct GraphConcept
  {
    typedef typename boost::graph_traits<G>::vertex_descriptor vertex_descriptor;
    typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor;
..blah...
    void constraints() {
      function_requires< DefaultConstructibleConcept >();
      function_requires< EqualityComparableConcept >();
      function_requires< AssignableConcept >();
...blah....
}
    G g;
  };
And produce something that looks like:
typedef adjacency_list MyGraphType;
What do you mean?  You want to add methods/functions to the graph type to 
make it model a specific concept?

-- Jeremiah Willcock