Re: [boost] [Graph] suggestion: rename distance_zero() to distance_identity()

From: Brook Milligan (brook_at_[hidden])
Date: 2007-09-19 09:37:53

Andrew Sutton writes:
 > I mostly agree, but I think we can do better too. One of the reasons  
 > that it probably took the name distance_zero() is that there haven't  
 > been many motivating examples of non-additive combinations of  
 > distance (and hence identities).

I suspect that you are right in that regard as most mathematical
algorithms are specified in terms of summations.  However, I ran into
the more general case when I tried to develop generic graph-based
algorithms for probability models, which require products.  There is
one example included in the probability library I have developed,
which is described at:

      http://biology.nmsu.edu/software/probability/

 > I'm wondering if it might not be worthwhile to build simple  
 > structures that provide the function types and constants for these  
 > algorithms rather than specifying them as distinct parameters. For  
 > the common case, these would simply default to the basic additive  
 > operations and identities but could be easily overridden.

By this I take it that you mean something along the lines of
std:limits<> that defines various properties of the type?  That would
certainly better integrate the concepts and simplify the graph
algorithm interfaces.

Cheers,
Brook