Re: [Boost-users] [graph] [python]

From: David E. Konerding (dekonerding_at_[hidden])
Date: 2006-02-27 17:09:12

Doug Gregor wrote:
>
>> As you can see, v1 and v2 return and have different addresses than the
>> Vertex objects that are listed by the vertices
>> iterator.  My guess here is that the Vertex objects do point to the 
>> same
>> underlying vertex in the C++ implementation
>> of the graph.
>>     
>
> Your guess is correct. We don't cache the Python objects corresponding 
> to vertex and edge descriptors.
>   

Ah.  OK.  Well, I guess that leads me to my next question.  I am writing 
a model-view graph editor using bgl-python (which the model
implemented as a boost graph).  Originally my idea was to keep the 
mapping between on-screen widgets and the graph vertices they corresponded
to in a dictionary:

self._widgetmap[vertex] = widget

However, since Vertex objects aren't cached, placing the vertex object I 
get back from add_vertex obviously isn't going to work.

I got to thinking, and it seems to me like the 'right way' to do this 
would be to invert the problem (somewhat violating the model/view 
abstraction):
add a vertex property map to the graph with mappings from the graph 
vertex object to the widget.  I can't see another way to do it
if Vertex objects aren't cached.

Dave