Using the Boost library as it currently stands, it appears the best way to abort the algorithm is to throw an exception.

Granted. I'd even go so far as to say "the only way" (based on my vast experience... I've actaully vistor's code once).

Whether or not throwing an exception is acceptable from a general programming standpoint is a topic more suited to a general C++ discussion list

Any recommendations? Preffereably something with an archive/FAQ so we don't drag up Holy War #42... --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;