[Boost.Graph] graph.vertices property creates new objects

[George Sakkis]

I've just started toying 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.ne xt() == v

True

>>g.vertices.ne xt() 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 ?

George

[Szabolcs Nagy]

Re: [Boost.Graph] graph.vertices property creates new objects

It seems that the vertices iterator creates new vertex objects every

time instead of iterating over the existing ones. This essentially

i don't know much about bgl, but this is possible since vertices are
most likely not stored as python objects inside boost

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 ?

that sounds bad, fortunately __hash__ can be overriden so even if id()
differs hash() can be the same for the same vertex.
if __hash__ is not handled then it's a bug in bgl imho.