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List:       boost-users
Subject:    Re: [Boost-users] accessing internal graph properties
From:       Sebastian Weber <sebastian.weber () physik ! tu-darmstadt ! de>
Date:       2004-11-29 17:28:49
Message-ID: 41AB5C51.6090703 () physik ! tu-darmstadt ! de
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> We considered this syntax (you might be able to find the discussion on 
> the Boost developers list; GMane is running a bit slow for me at the 
> moment). The basic problem is that we would need both const- and 

actually I do not unterstand that point, but well, I guess I am to new 
to the BGL to get that.

> On the performance side, it would make copying descriptors more 
> expensive (e.g., with VertexListS=vecS, a vertex descriptor is just an 
> integer; it would have to go to _at least_ a pointer). On the other 
> side, I don't see that this would help performance much when accessing 
> internal properties.

Well, it does help! Since I got a workaround to that problem: I checked 
the code of the adjacency_list.hpp a bit and got the idea how I can save the

boost_graph[vertex_descriptor]

lookup to my desired internal property object: by storing pointers to 
just that returned object, which is of type Spot* in my example. This 
works great and speeds up my application at least a bit. If you are 
interested in some code, you are surely welcome.


Greetings,

Sebastian Weber


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