Question

I found a very useful answer on how to create templated graphs using boost::graph under Modifying vertex properties in a Boost::Graph

For me, this is very convenient as long as I do all the work on the graph in the Graph-class itself.

However, it might be necessary to access information from outside, e.g. one might want to implement a Printer-class that takes a Graph-object and prints out all the stored information.

In that case, it could be handy to access all the vertices (e.g. by a vertex iterator). Unfortunately, this won’t work, as all the typedef is done in the Graph-class and this information is not accessible from outside, so the Printer-class won’t know what a vertex-iterator etc. is.

How could I address this issue and still keep the templated aspect?

Thanks.

Answer 1

But the typedefs are public, so you can access them from outside:

template<typename T>
class A
{
public:
    typedef T type;
    typedef unsigned data;
};

Now this is the following:

A<int>::type // int
A<int>::data // unsigned

Be careful, if T is not specified

template<typename T>
void func( A<T>& a )
{
    typename A<T>::type // T
    typename A<T>::data // unsigned
}