Re: [boost] [BGL] depth_first_visitor improvement?

From: Vladimir Prus (ghost_at_[hidden])
Date: 2002-01-25 11:01:05

David Abrahams wrote:

> > Thanks! This will do for my case. However, I feel like this is not very
> > direct way to accomplish the task. Further, it's less efficient as it
> > would
> > require examining vertex label once for each out-edge, not once for each
> > search. Okay, I agree that this might not be a problem in practice.
>
> Here's another thought:
>
> Just make sure the filtered_graph is specialized on a user-defined
> predicate type, then define an out_edges() function for this specialized
> graph which returns an empty range when the source vertex is labelled. The
> filtering predicate will never get used; it's just there to make sure you
> "own" the filtered_graph type.

It's not that simple. Since labels is not internal property (and it makes 
little sense), I can't just specialize out_edges. I'd need to create a new 
graph type which ctor will take labels, or I'll need to create a new type of 
graph, which will have labels as internal property and make a copy of the 
original. Hmm... that's too complicated... settled on simple filtered_graph 
for now. Actually, I would be very good if I could add property maps to a 
graph at runtime.

- Volodya