How to factorize common fields with deform/colander ?

Question

I need to display two forms depending on the context. The second form should contain a name and email text input followed by the first form content in that order, but only when the user is not authenticated.

I tried with Python class inheritance but in every tested cases the two new fields were displayed after the content of the first form.

Is there a way to correcly factorise common fields in deform forms or to specify a different display order?

Answer 1

The solution is probably to define the schema imperatively:

http://docs.pylonsproject.org/projects/colander/en/latest/basics.html#defining-a-schema-imperatively