Zero-copy output for filters
This issue is in reference to the in-progress Filter classes. The use of a policy to describe custom inputs is great; there should probably be something similar to describe custom outputs. Robert and I have discussed how this could go, and one idea was the use of output generator classes that can populate output datasets. This would facilitate the filling of externally created containers (or, at least, instructions on how to initialize output containers), rather than constructing default-initialized output data arrays.