Produits Entr'ouvert » Authentic 2

For now new attribute kinds are defined from config.py, like this:

from django import forms

class NrnField(forms.CharField):
    def validate(self, value):
        super(NrnField, self).validate(value)
        if not value:
            return
        try:
            if (97 - int(value[:9]) % 97) != int(value[-2:]):
                raise ValueError()
        except ValueError:
            raise forms.ValidationError("Invalid format")

A2_ATTRIBUTE_KINDS = [{
            'label': u'National Register Number',
            'name': 'nrn',
            'field_class': NrnField,
        }]

but I'd prefer to have this in a proper module.

I'm guessing we'd need a new extension point in plugins and change get_attribute_kinds to chain through them, but maybe you have a different suggestion?