[tijsvd]

Sure that makes some sense.

But it's somewhat ugly as well, from an architecture point of view. Because that argument translates to anything else you might want to do with these objects.

In past libraries for C++ I've tried to prevent this kind of coupling by adding generated template methods like "walk(f)" where f would be a templated callable, called with a descriptor and data reference for each field. Any kind of pretty printer or SQL statement can be built that way.