Hugo Duncan wrote:
Ideally, though, I was looking for a solution that allowed me to reuse the delay buffer without modifying it. That way it could be used as a lower layer for any algorithm that needed recent time history. Maybe I am being over ambitious... The coupling of the cache_size and the coefficients parameters has to be expressed in code somewhere. Where do you suggest?
It would be nice to do it in the filter code. The coefficents parameter is a parameter of the filter after all, and the use of the delay can be looked at as an implementation detail. If the filter constructor (body) could access the delay buffer, then the delay buffer could expose a method to allow resizing. Is that possible?
Ah, ok. Yes, that's possible. In the version you have, that would be done with a post-constructor. In the post-review version (which I haven't made available yet), post-constructors are dead, accumulators within the set are guaranteed to be constructed only after the accumulators on which they depend are constructed, and the entire accumulator_set is available in the argument pack. You'd basically do something like: template<class Args> filter_impl(Args const &args) : ... { // filter depends on delay_buffer, so delay_buffer is // guaranteed to be constructed already. find_accumulator<tag::delay_buffer>(args[accumulator]). resize(boost::size(args[coefficients])); } I'll try to package up the latest version of accumulators Real Soon. If you can't wait, just put the same code in a member function called post_construct and it should do the right thing. Either way, you'll need to write your delay_buffer_impl so that it works when cache_size is not specified. -- Eric Niebler Boost Consulting www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com