WeightType is misleading in boost::random::discrete_distribution

[Tim White <boost.10.wtwhite@…>]

The class template boost::random::discrete_distribution is parameterized by types IntType (defaulting to int) and WeightType (defaulting to double). Could you please update the documentation to clarify that WeightType must be a floating-point type? Alternatively, if the implementation could be changed to allow integer WeightTypes that would be even better! (But I imagine that could be a lot of work.)

A bit more background:

The documentation doesn't give any constraints on WeightType, and in fact the documentation for one of the constructors gives as an example

discrete_distribution<> dist{1, 4, 5};

which indicates that weights don't have to sum to 1, and hints at the possibility of using an integer WeightType -- which would often be convenient and efficient. However, the following snippet fails compilation:

#include <boost/random.hpp>
void f() {
    int w[] = {1, 4, 5};
    boost::random::discrete_distribution<int, int> dist(w, w + 3);
}

Changing the <int, int> to <int, double> or just <int> enables compilation. (Also, looking at the Boost implementation, I see a call to an internal normalize() method that divides all weights by their sum, so it looks like support for integer WeightTypes was never intended.)

Thanks, Tim

[Steven Watanabe]

I intended to support integer weight types, but it requires a separate implementation and I haven't gotten around to it yet.

[Steven Watanabe]

Fixed in ​http://github.com/boostorg/random/commit/dbb7b3cfaa938a38ed012c924d5ceeafb3357691.