Variable Iterator. Iterates over variables of a category, with the
foreach delegate being called with the name of the category (not
including the root string prefix) and an instance containing the
properties within that category.
intopApply(int delegate(ref istring name, ref T x) dg)
Variable Iterator. Iterates over variables of a category, with the foreach delegate being called with the name of the category (not including the root string prefix) and an instance containing the properties within that category.