John Maddock wrote:
In the tutorial it says:
" Even the extractors can accept named parameters. In a bit, we'll see a situation where that is useful."
But I can't find any further mention of extractors with named parameters, I ask because I believe it may be indeed be useful - for example a student's t test could defer requiring the acceptable risk level until the extractor is actually called - so the same test could be conducted multiple times with different risk levels for example just by calling the extractor multiple times.
Whoops. I had intended to document how to use an external accumulator for the weight statistics, which can then be passed in as a parameter at extraction time. (Essentially, dependencies within an accumulator set can be resolved by promising to pass in the required accumulator at extraction time.) But apparently I never got around to it. I'll fix that.
One other thing I've missed is the ability to "reset" an accumulator so it can be used more than once. Is this possible? Potentially it might save quite a bit of construction cost in some cases?
Would you like to be able to reset an accumulator, or the whole set? Nothing stops you from writing an accumulator with a reset() member function. You can use accumulator_set::extract() to fetch the accumulator corresponding to a certain feature and then call reset() on it. It might be nice to have an accumulator_set::reset() member function that resets all the accumulators in order. But what should happen to accumulators that don't define a reset() function? Destroy and reconstruct them in-place? That could be trouble. Skipping them would be trouble, too. -- Eric Niebler Boost Consulting www.boost-consulting.com