Re: [Boost-users] [BGL] vertices creates new objects

From: Doug Gregor (dgregor_at_[hidden])
Date: 2007-01-29 15:15:37

On Jan 29, 2007, at 12:52 AM, George Sakkis wrote:

> I've just started playing with the python bindings of BGL and I'm
> puzzled from the following:
>
>>>> from  boost.graph import Graph
>>>> g = Graph()
>>>> v = g.add_vertex()
>>>> g.vertices.next() == v
> True
>>>> g.vertices.next() is v
> False
>
> It seems that the vertices iterator creates new vertex objects every
> time instead of iterating over the existing ones. This essentially
> prevents, among other things, storing vertices as keys in a dictionary
> since the hashes of the stored and the new vertex differ although they
> compare equal. Is this really what's happening, and if so, why ?

The latest version of the BGL-Python bindings, available in the  
Subversion repository, re-uses vertex and edge descriptors, so the  
last check would return "True". This is what we should have been  
doing all along.

        Cheers,
        Doug