On Feb 6, 2005, at 11:36 PM, Eelis van der Weegen wrote:
Analysis:
vec_adj_list_impl's operator= calls this->clear() followed by copy_impl(x), where x is the vec_adj_list_impl that is being assigned from. copy_impl(x) _adds_ x's vertices and edges to this->m_vertices and this->m_edges. Therefore, it would seem that clear() should clear both of those. While clear() does immediately do m_vertices.clear(), it doesn't clear m_edges directly, but instead calls clear_dispatch(edge_property_type()). There are two overloads for clear_dispatch(): one function template parameterized by the property type, and a non-template overload that accepts a reference to const no_property. While the former immediately calls m_edges.clear(), the latter does nothing (empty function body). Consequently, in graphs whose edge_property_type is no_property, the edges from 'x' mentioned above are added to the currently existing edges, while they should replace them.
Thanks for the analysis!
Since I don't know the purpose of the clear_dispatch() overload for no_property, I have no idea what the solution should be.
Once upon a time, there was an optimization in adjacency_list to handle the no_property case. It didn't work, so it was pulled out. Unfortunately, it seems that it wasn't completely removed :( I've checked in a fix. Doug