John Maddock wrote:
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).
I don't understand this, it has to do with my lack of knowledge on this... If you ensure that the parameters get checked in the constructor, why would that check *not* throw an error when needed? Compile time might be tricky depending on the complicity of the parameter validation code, but simple range check on the parameters could be done compile time. What mechanism are your thinking about regarding compile checking, e.g. that scale>0?
I'll work out the parameter idea in the Laplace distribution code...
OK good.
John, I got a bit of Laplace code to share! I still need to test the numerical results, but I compiles without errors/warnings, and it throws errors when parameters are invalid. Do I need to put the code somewhere? I've attached it to this mail... I have 3 idea's in the code I'd like to discuss. * a public member function "check_parameters" in the distribution class * a public member function operator() that allows run-time changing of dist parameters. I know that's a big change... I myself could use something like this. E.g. I have some code that calibrates a stochastic model based on time series data & stores the estimated distribution parameters in a file. Another program will read the distribution parameters from that file, crate distributions objects, and do probability calculations with that. I can only do that when I can set the distribution parameters *runtime*. * no more checking for distribution parameters in the non-member functions. Checking is only done when the distribution parameters get set or get changed. But as said before, I have no good grasp on the subtle issues with that. You said "if we could figure out whether the error handlers will throw or not", implying that there are complexities with this. At the moment, I just have the code. It you think the code is ok, then how would I go about with documentation & testing? Do you have some structure in place for that? I've seen quite some code in the sandbox/math, ...concept etc... Cheers, Thijs