Hugo Duncan wrote:
Given recent discussion on Time Series and Accumulators, I thought I would have a go at implementing a FIR filter for Accumulators, and have run into a problem.
I decided to do this in two parts; first create a (reusable) delay statistic (similar to tail) that provides a history buffer for the signal and then create the filter (similar to tail_variate) , that will depend on the delay buffer.
I have created the delay buffer with a length determined by a cache_size argument. This works well.
I am now creating the filter, which has a "coefficents" argument to set the filter coefficients. I would like to pass the size of the coefficients list as the cache_size argument to the underlying delay buffer.
Is this possible?
Certainly. You can use Boost.Parameter to define a new keyword: BOOST_PARAMETER_NAME(coefficients) The accumulator_set has constructors that take named parameters and builds and argument pack. accumulator_set<... > acc( ..., coefficients = 5, ...); The resulting argument pack is passed as the constructor parameter to all the accumulators in the set. Your accumulator can then extract the coefficients argument from the pack with "args[coefficients]". HTH, -- Eric Niebler Boost Consulting www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com