Subject: Re: [boost] [UUID] version v12
From: Johannes Brunen (JBrunen_at_[hidden])
Date: 2008-10-13 07:12:02
Hello Andy,
after some investigations, I think that I have found the origin of the
problem:
In seed_rng.hpp the following code is used:
template <typename UniformRandomNumberGenerator>
inline void seed(UniformRandomNumberGenerator& rng)
{
seed_rng seed_gen;
boost::generator_iterator<seed_rng> begin(&seed_gen);
boost::generator_iterator<seed_rng> end;
rng.seed(begin, end);
}
Problematic is the construction of the end iterator. Looking into the code
(boost/generator_iterator.hpp) shows, that the default constructor of
generator_iterator does not initialize its member variables.
generator_iterator() {}
Howerver, the mersenne_twister seed code does compare the two given
iterators as shown below (boost/random/).
template<class It>
void seed(It& first, It last)
{
int j;
for(j = 0; j < n && first != last; ++j, ++first)
x[j] = *first;
i = n;
if(first == last && j < n)
throw std::invalid_argument("mersenne_twister::seed");
}
As the end iterator is not initialized the way is open for all throwing the
invalid_argument exception.
Locally, I did solve the problem by patching the default constructor of
class generator_iterator.
If this is a valid solution of the problem, it would be fine if anyone
applies the correction to the boost code.
Greetings,
Johannes