-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of John Maddock Sent: 22 November 2008 09:55 To: boost@lists.boost.org Subject: Re: [boost] [math distributions] where to check for validity of distribution variables?
Thijs van den Berg wrote:
What do you think? We might turn "having valid parameters" into a property of *all* distribution. As an alternative, we might add a non member function bool valid<distributionType... but that wouldn't allow for caching validation in e.g. a constructor
Sounds fine to me. thats great! What's your opinion on the fact that you can only set parameter in the constructor? E.g. the normal distribution does a parameter check in the constructor, and those parameters can't change after that.
That's what the existing distributions do. In fact we could omit most of the subsequent parameter checking code if we could figure out whether the error handlers will throw or not on error (in fact we *can* get this information at compile time and make the subsequent checks a no-op if we know that the constructor would have thrown on error... we just ran out of time on that refinement).
As I recall, we figured that the time it saved compared with the mega-whirring that would follow was negligible. What was important was to catch dud parameters, so checking even if redundantly was worth it. Paul --- Paul A. Bristow Prizet Farmhouse Kendal, UK LA8 8AB +44 1539 561830, mobile +44 7714330204 pbristow@hetp.u-net.com