Re: [Boost-users] Extend boost::adjacency_list

Subject: Re: [Boost-users] Extend boost::adjacency_list
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2011-10-03 17:28:27

On Mon, 3 Oct 2011, Jupp Tscheak wrote:

> Dear users of boost graph library,
> I would like to extend boost::adjacency_list like this
> 
> code:
> class MyGraph:
>     public boost::adjacency_list<boost::multisetS,
>                                  boost::vecS,
>                                  boost::bidirectionalS,
>                                  boost::property<boost::some_vertex_property, SomeVertexProperty*>,
>                                  boost::property<boost::some_edge_property, SomeEdgeProperty*> {}
> 
> This works as expected.
> 
> Is it possible to extend class "MyGraph" with additional vertex and/or edge properties defined?
> 
> My first approach was like this
> 
> code:
> template <class AdditionalVertexProperty = boost::no_property, class AdditionalEdgeProperty = boost::no_property>
> class MyGraph:
>     public boost::adjacency_list<boost::multisetS,
>                                  boost::vecS,
>                                  boost::bidirectionalS,
>                                  boost::property<boost::some_vertex_property, SomeVertexProperty*, AdditionalVertexProperty>,
>                                  boost::property<boost::some_edge_property, SomeEdgeProperty*, AdditionalEdgeProperty> {}
> 
> class ExtendedMyGraph: public MyGraph<boost::property<boost::some_add_vertex_property, SomeAddVertexProperty*> > {}
> 
> 
> This, however, led into multiple compiler errors. Does anyone know how to achieve the wanted behavior?

It is unsafe to subclass BGL graph types.  However, you can define a 
metafunction that does what you want:

template <typename VP = boost::no_property, typename EP = boost::no_property>
struct gen_MyGraph {
   typedef <your big adjacency_list type> type;
};

and then use gen_MyGraph<boost::property<...> >::type as your graph type.

-- Jeremiah Willcock