Am 07.09.2010, 06:56 Uhr, schrieb Tim Hoffman <>:

> So in my contrived example I would like the set of possible values
> for color is dependent on the
> user and some other factor.  Looking at the code for SelectWidget and
> RadioChoice widget
> it appears they won't take a callable and lazily render those values
> at render time.


do you mean in a similar way to the way a vocabulary works in zope.schema?  
I discussed this a while back with Chris and the reason why this often  
extremely useful feature isn't built into deform is that deform on its own  
has no context. I have written something similar - a callable that works  
both as a validator for Schema nodes and as values for widgets:

class Source(object):
     """Utility for vocabulary constraints"""

     def __init__(self, values):
         """Can be initialised from a dictionary, a list of tuples
         or a list"""
         if hasattr(values, 'items'):
             self.values = values.items()
         elif hasattr(values, 'append'):
                 self.values = values
             except ValueError:
                 self.values = enumerate(values)

     def __call__(self, value):
         return value in self.values

     def __iter__(self):
         return self.values.__iter__()

colours = Source(
                ['red, blue, green']

class MySchema(MappingSchema):

       colour = SchemaNode(
                 title=u'Travel details',

class Form(object):

     def __init__(self, context, request):
         self.context = context
         self.request = request

     form = Form(MySchema(), buttons=(u'submit',))
     form['lift'].widget = widget.RadioChoiceWidget(values=colours)

     def __call__(self):
         html = self.form.render()
         return {'form':html}

I don't know how much of this could be truly dynamic.

Charlie Clark
Managing Director
Clark Consulting & Research
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