Re: [Boost-users] BGL problem, originally [Another C++inheritence/polymorphism problem]

From: Douglas Gregor (dgregor_at_[hidden])
Date: 2005-02-11 22:49:08

On Feb 11, 2005, at 6:00 PM, Welson Sun wrote:
>   template <typename Vertex>
>   void operator()(std::ostream& out, Vertex& v) {
>     out << "[label=\""
>         << g[v].toString()
>         << "\"]";
> [snip]
>   template <typename Edge>
>   void operator()(std::ostream& out, Edge& v) {
>     out << "[label=\""
>         << "E"
>         << "\"]";
>   }

I think it's a problem with the reference... typically, you just accept 
vertex and edge descriptors by-value (not by-reference), because 
they're small and cheap to copy. So the second operator() would start 
with:

   template<typename Edge>
   void operator()(std::ostream& out, Edge v) {

        Doug