[Boost-users] Re: newbie: Graph library - bundled properties

From: Jeffrey Holle (jeff.holle_at_[hidden])
Date: 2004-11-23 18:24:19

Interesting.  I will have to check out the new 1.32.0 stuff.

The subgraph issue that I mentioned may need more of an explaination.
I create derived subgraphs with create_subgraph(VertexIterator first, 
VertexIterator last) method of subgraph.  This causes the edges that are 
"local" to the included vertex descriptors to be added to this derived 
subgraph.

I find that internal properties of such a graph are not those of the 
base(root) graph.  I know this because my property classes hold an 
interface pointer which is NULL when constructed with the default 
constructor.  In my application, this is an invalid object which causes 
segment faults to occur.

I've another issue that I'd really like to see changed.
It has to do with the connected_components.hpp algorithm.
There is a concept check, at line 99, which insists that the type of 
graph be undirected.  I have to comment this line out every time I 
update my boost library.

In my application, my graph is bidirectional.
I am writting a diagram layout procedure and need to split the problem 
into multiple graphs if there are isolated components in the original 
graph because my layout algorithm only works on connected graphs.

I've tried the other connected algorithms and they do not provide the 
proper answer for this application.

I'd like to add both these issues to a bug system.
Can you provide a link?

Doug Gregor wrote:
> 
> On Nov 23, 2004, at 3:51 PM, Jeffrey Holle wrote:
> 
>> You are not properly introducing your custom properties to boost.graph.
> 
> [snip]
> 
>> Your code example sugguests you expect things like operator[] methods 
>> where they aren't.  I too like to code in this fashion.
> 
> 
> Actually, we've improved this in the BGL, so that the operator[] methods 
> do work for adjacency lists and adjacency matrices when using bundled 
> properties. Check out the new stuff in 1.32.0 :)
> 
> As for the other poster's question... I'll try to answer that later, but 
> I think the problem is that bundled properties aren't support for the 
> graph properties (e.g., the graph name), whereas they are supported for 
> edges and vertices. This will probably change in a future revision.
> 
>> Note that this class holds a boost subgraph by reference and accesses 
>> properties only through the root subgraph.  I found this necessary in 
>> boost 1.31_0 because the properties of "derived" subgraphs had only 
>> default contructed property classes.  If this has been fixed in boost 
>> 1.32_0, I'd like to know about it.
> 
> 
> This is a subgraph issue? We'll try to tackle this for 1.33.0; is the 
> bug in the Sourceforge bug tracker?
> 
>     Doug