[boost] [BGL] null vertex?

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-05-29 09:20:52

I think that it would be handy to introduce "null vertex value" into BGL. For 
example, I'm computing some 'alternative vertices' in some function. If no 
such vertex exists, I'd like to record this fact, so that when the function 
is called again on the same vertex, I don't have to do anything. I'd like to 
write

  alternative[v] = null_vertex(g);

or something similiar. This is feasible: if vertex_descirptor is pointer, you 
have a natural value for null. If vertex descriptor is interger, well... you 
can use index 0 for null vertex. This would waste a bit of space, but is it 
that important?

Opinions?

- Volodya