On Sun, 1 Jan 2012, Jens Müller wrote:
Hi all,
I'm currently fixing up leda_graph.hpp so it passes the tests, or indeed, fixing the tests ...
A leda::GRAPH<int,int> (=Graph) has to fulfill VertexListGraphConcept. This means that boost::graph_traits<G>::vertex_iterator has to be a MultiPassInputIterator, i.e., also a InputIterator.
I cannot read from http://www.sgi.com/tech/stl/InputIterator.html that it must be possible that you can compute the difference between two iterators.
But apparently the concept check (which fails) requires a difference type, which must be a signed integer. Is this a bug in the concept check?
You need the difference_type defined (to be the result of std::distance, for example) but not the operator-() to compute the distance itself (nor the other random access operators such as +). -- Jeremiah Willcock