AMDG John Phillips wrote:
The formal review of the Boost.Accumulators library, submitted by Eric Neibler begins today and ends on Wednesday, February 7. The library is available from
http://boost-consulting.com/vault/index.php?directory=Math%20-%20Numerics
From the documentation:
Boost.Accumulators is both a library for incremental statistical computation as well as an extensible framework for incremental calculation in general. The library deals primarily with the concept of an accumulator, which is a primitive computational entity that accepts data one sample at a time and maintains some internal state. These accumulators may offload some of their computations on other accumulators, on which they depend. Accumulators are grouped within an accumulator set. Boost.Accumulators resolves the inter-dependencies between accumulators in a set and ensures that accumulators are processed in the proper order.
Your comments may be brief or lengthy. If you identify problems along the way, please note if they are minor, serious, or showstoppers.
Here are some questions you might want to answer in your review: ? What is your evaluation of the design? ? What is your evaluation of the implementation? ? What is your evaluation of the documentation? ? What is your evaluation of the potential usefulness of the library? ? Did you try to use the library? With what compiler? Did you have any problems? ? How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? ? Are you knowledgeable about the problem domain?
And finally, every review should answer this question: ? Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion.
All interested parties are encouraged to submit a review. These can be sent to the developer list, the user list, or if you don't want to share your review with the general public it can be sent directly to me.
Thanks to all for the work you will do on this review.
John Phillips Review Manager user_s_guide.html#id450311 line 363 accumulators.qbk line 189 for some reason external<> is not a link in the html
accum_set; accum_set(1.0); accum_set(2.0); accum_set.drop<tag::sum>(); accum_set(3.0); std::cout << mean(accum_set) << std::endl; //prints 1 } This behavior can easily cause surprises. It must be fixed to print 2. I'm not quite sure how to implement it correctly. I think that probably you need to store the result at the point that drop is called for external lookup and continue to collect data for internal usage. Of course,
accumulators.qbk lines 35-37 [def _mpl_ [@../../libs/mpl MPL]] [def _mpl_lambda_expression_ [@../../libs/mpl/doc/refmanual/lambda-expression.html MPL Lambda Expression]] [def _parameters_ [@../../libs/parameters Boost.Parameters]] these links are bad post_construct() Unless for some obscure reason that I am missing it is just too difficult, I would strongly prefer to make sure the constructors are called in the correct order. The whole dance with fusion::vector is unnecessary. It would be simpler to use struct accumulator_tuple_base { template<class Args> accumulator_tuple(const Args&) {} } template<class T, class Base> struct accumulator_tuple : T, Base { template<class Args> accumulator_tuple(const Args& args) : T(args), Base(args) {} }; Since every accumulator is put before all the accumulators that depend on it in make_accumulator_tuple you can write typedef typename mpl::reverse_fold< sorted_accumulator_vector , accumulator_tuple_base , accumulator_tuple<mpl::_2, mpl::_1> >::type type; Then every accumulator is constructed after any others that it depends on. As a bonus the only limit to the number of accumulators is whatever the compiler can handle. What happens if you freeze a feature that another feature depends on? #include <iostream> #include <boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/mean.hpp> #include <boost/accumulators/statistics/sum.hpp> using namespace boost::accumulators; int main() { accumulator_set<double, features<tag::mean, droppable<tag::sum> this only applies in the face of dependencies. The user guide needs to specify what header each component is in. BOOST_PARAMETER_NESTED_KEYWORD.html There is no description of what this macro is for. accumulator_set.hpp line 149 corresponds to -- What? accumulators_fwd.hpp #define's FUSION_MAX_VECTOR_SIZE/FUSION_MAX_TUPLE_SIZE This is a very bad idea as it might make make the value smaller than it would otherwise have been. Please just check FUSION_MAX_VECTOR_SIZE and issue a #error directive if it is too small. For simple cases at least the library seems to cause little to no overhead with msvc compared to hard coding everything. The docs need to state clearly what happens when more than one accumulator maps to the same feature. Overall the users guide is quite good. I had no difficulty understanding it. The reference manual is pretty sketchy though. For the most part the interface is clean and easy to use. I definitely think Accumulators should be included in boost. In Christ, Steven Watanabe