Plone won't start when I try to get values from my registry

[zopyx (Andreas Jung)]

What is the sense of this @implementer decorator without interface?

See also this with a working code example:

IContextSourceBinder and validation in Plone 5.2

We use IContextSourceBinder frequently e.g. form.widget("gl_refs_my_onkopedia", SelectWidget, multiple="multiple") gl_refs_my_onkopedia = schema.List( title=_("References to My-Onkopedia"), description=_("References to My-Onkopedia"), required=False, value_type=schema.Choice( source=OnkopediaPathBinder(["my-onkopedia", "mein-onkopedia"]) ), default=[], ) with @implementer(IContextSourceBinder) class OnkopediaPathBinder(ob…